Ongoing projects

Tunable opto-electronics in periodically strained two-dimensional materials. 01/11/2020 - 31/10/2022

Abstract

Periodic structures and flat bands realized experimentally in two-dimensional (2D) materials have recently proven to be a fertile ground for novel physics. I will take advantage of existing expertise and collaborations at CMT research group in order to propose periodically strained configurations of 2D materials, e.g. graphene, transition metal dichalcogenides or phosphorene, for the purpose of exploring novel opto-electronic phenomena related to (flat) electronic mini-bands or excitonic bands. To do so, I will first use numerical simulations to investigate how strong periodic strain modulations of several types can be engineered in 2D materials. Then, I will assess how these different types of modulations introduce band renormalization and how the latter, in its turn, affects optical and electronic properties of the 2D crystals in monolayer and multilayer form. In doing so, I will also be able to relate the role of external effects, such as applied electric fields, to the opto-electronic properties of these strained crystals. The external fields and periodic strains can function as a tuning knob for the opto-electronic response. Finally, I will investigate more deeply how periodic strain fields affect its excitonic properties. In this project, I will make use of the close collaborations of the CMT group with various experimental groups worldwide. The research is theoretical in nature, but I will repeatedly link my results to experiments to maximize impact of the research.

Researcher(s)

Research team(s)

Dormant chirality in magnetic two-dimensional materials. 01/11/2020 - 31/10/2021

Abstract

It is well known that magnetic exchange interaction drives the behavior of magnetic materials, making them ferromagnetic (positive interaction, spins parallel) or antiferromagnetic (negative interaction, spins antiparallel). It is far less obvious that there exist components of exchange interaction that lead to chiral magnetism, i.e. causing the adjacent spins to assume orthogonal mutual ordering. Dzyaloshinskii-Moriya interaction (DMI) is one such interaction, first identified in the 60's, but it was only the recent observation of skyrmion lattices that instigated its further fundamental research and technological applications. DMI can only arise in systems that lack inversion symmetry and host strong spin-orbit coupling, a condition that is met in few bulk materials, and at interfaces of specifically designed magnetic heterostructures. In 2017, magnetic ordering was also observed in 2D materials, CrI3 being the first. There, magnetic atoms (Cr) are in direct bonding with non-magnetic atoms with strong spin-orbit coupling (I). Therefore DMI must be intrinsically present but is cancelled out in a perfect crystalline lattice so there is no apparent DMI, unless symmetry is broken (at the edges, defects, grain boundaries etc.). What are the microscopic mechanisms to awaken such a dormant DMI, how significant it can be, and how to tailor its release and the corresponding spin textures as a function of temperature and magnetic field, are the overarching themes in this project.

Researcher(s)

Research team(s)

Piezo and flexoelectricity driven by inhomogeneous strain in 2D materials. 01/10/2020 - 30/09/2023

Abstract

Electromechanical properties play an essential role in determining the physics of dielectric solids and their practical application. Popularly, electrostriction, and the piezoelectric effect were considered to be the two main electromechanical effects that couple an applied electric field to the strain and vice versa. The coupling between polarization and strain gradients is another electromechanical phenomenon, which can be observed by bending a material. This is known as flexoelectricity, which is present in a much wider variety of materials, including non-polar dielectrics and polymers, but is only significant at small length-scales, where high strain-gradients develop. In two dimensional (2D) materials, where large strain gradients are possible, these effects are expected to be strongly enhanced. Besides, the superior elastic properties and reduced lattice symmetry makes 2D materials promising for flexoelectricity. In this proposal, by using state of the art ab initio approaches, fundamental flexoelectric properties of a wide variety of 2D materials will be investigated. Subsequently, a multiscale modeling framework that captures the influence of internal-strain gradients on the electronic and optical properties will be developed. The work proposed here will not only provide a fundamental understanding of flexoelectricity in 2D materials but will also guide the discovery of new flexible electronics.

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Research team(s)

Emerging phases of interlayer excitons in bilayers with flattened electronic bands. 01/10/2020 - 30/09/2023

Abstract

Recent experimental results on superconductivity in twisted bilayer graphene indicates that flat bands are a key feature to explore strongly correlated phases. A straightforward access to quasi-flat bands has also been realised by means of twisting or periodic straining in van der Waals heterobilayers made of transition metal dichalcogenides. By controlling the doping in bilayer systems, it is possible to generate interlayer excitons: electrons are confined in a layer and couples with holes, confined in the opposite and separated layer. In this project, I propose to theoretically study the effects of tunable flat bands on interlayer excitons with the aim to investigate the emergence of excitonic strongly correlated phases. At low temperature, a number of competing phases have been predicted, including electron-hole superfluidity, exciton insulator, coupled Wigner crystallisation and charged density waves. The enhancement of the effective masses of the carriers increases of the excitonic binding energy and this makes the excitonic phases more robust. By tuning the flatness of the bands it will become possible to enhance the critical temperature for electron-hole superfluidity and to control the emergence of the competing strongly correlated phases that appear in the phase diagram.

Researcher(s)

Research team(s)

Skyrmionics and magnonics in heterochiral magnetic films – a multiscale approach. 15/07/2020 - 14/07/2021

Abstract

Through this DOCPRO1 project, the PhD student will finalize his thesis on heterochiral magnetic films, based on the just developed generalized Heisenberg methodology on an arbitrary lattice, enabling him to broadly explore the magnetic phase diagram of mono- and bi-layer spin-lattice systems with spatially nonuniform chirality. This study is motivated by recently discovered 2D magnetic materials, their lattice structure, anisotropy, emergent chirality, and geometrical manipulations known to van der Waals engineering. Besides the generic topological characterization and classification of the possible spin textures, attention will be paid to the emergent spin-wave (magnonic) properties in the given spin landscape and novel concepts for spintronic devices.

Researcher(s)

Research team(s)

Emergent properties of 2D magnetic materials. 01/04/2020 - 31/03/2021

Abstract

This project aims to investigate the properties of recently emerged two-dimensional (2D) materials having intrinsic magnetism. Motivated by the recent discovery of the ferromagnetic 2D monolayer CrI3 and the found plethora of magnetic phase transitions with every added layer, we investigate the formation mechanism, the temperature dependence and the routes for tuning 2D magnetism by external stimuli such as strain, charge doping, and electric field, with an outlook to possible applications.

Researcher(s)

Research team(s)

'Robert Oppenheimer' - 2019 01/12/2019 - 31/12/2020

Abstract

Prize received from the University's research council. I will use it to enhance my research and allow students to explore the work I'm doing as well. This will allow me to spread what we are doing at our university.

Researcher(s)

Research team(s)

Ionic transport and phase transitions in alkali-intercalated two-dimensional materials under active manipulation. 01/11/2019 - 31/10/2021

Abstract

Ionic transport in low-dimensional materials plays the key role in novel concepts of energy harvesting and storage devices. Recent experimental progress allowed fabrication of extremely narrow (comparable to the size of an atom, where quantum effects dominate) and clean channels between 2D materials that are weakly bound together. The flow of ions or molecules is such channels was found to be extremely swift, which was attributed to high pressure induced by such a tight confinement. This pressure also made atoms pack closer together and produce a completely different composite structure by forming bonds with the confining material. The narrowness of the channels allows only a few layers of atoms to move through, in a fashion tunable by applied pressure, lateral strain, or electric field. Once understood, the advanced ionic transport under quantum confinement has potential to boost performance and capacity of batteries. Furthermore, the bonding of ions to the confining material can completely change the electronic phase of the system, so that it becomes e.g. superconducting at low temperatures, and useful for dissipationless electronics. Therefore, the main objective of my project is to investigate the mechanisms of ionic flow in strongly confined channels, how to manipulate ionic ordering and flow therein, and to identify the emergent phase transitions in the systems of interest – to enable novel concepts for blue-energy, miniaturized battery, and nanoelectronics applications

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Research team(s)

Tailoring plasmonics in van der Waals heterostructures. 01/10/2019 - 30/09/2022

Abstract

This research proposal aims at untangling and modelling the plasmonic properties of various van der Waals heterostructures and at using these models to construct new tailor-made structures that host unique types of plasmons. By changing the composition and structural properties of heterostructures, we will be able to uncover novel ways to manipulate light at sub-wavelength length scales by coupling it to collective excitations of the electron liquid, so-called plasmons. Van der Waals heterostructures are stacks of different types of atomically thin two-dimensional materials. In the wake of the discovery of graphene, a single layer of graphite, many other atomically thin crystals have been discovered and each of them has its own electronic behavior ranging from insulators over semiconductors and semimetals to even superconductors. We are now in a unique position to combine different two-dimensional crystals in a single stack and to construct tailor-made heterostructures in which the properties of the individual materials can be used in concert. In this project I will investigate various heterostructures in order to extend our understanding of the behavior of plasmons in these materials, and furthermore to uncover plasmons with unprecedented characteristics. The proposed work will be done in close collaboration with foreign experimental groups that will provide necessary feedback to improve the models and to test the plasmonic response of proposed heterostructures.

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Research team(s)

Computational modeling of materials: from atomistic properties to new functionalities. 01/01/2019 - 31/12/2023

Abstract

The WOG "Computational modeling of materials" aims to: - Promote interdisciplinary computational material research, bringing together groups from physics, chemistry and materials science, and providing them with a platform on which to share their expertise in order to arrive at an integrated and pragmatic approach in order to develop opto-electronic, thermodynamic and structural properties of materials to study. - Develop new techniques and implement them in computer software that can be subsequently used in either academic or industrial contexts

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Research team(s)

Tunable in-plane and out-of-plane anisotropy in two dimensional materials. 01/10/2018 - 30/09/2021

Abstract

Two-dimensional (2D) single-layer materials are currently a very important topic in materials science because of their unique properties. A particular class of such materials are one those with low symmetry and with anisotropy which are important candidates for various applications in nanotechnology ranging from optoelectronic to spin-based devices and even to field effect transistors (FET) and nano optical waveguide polarizers. The prediction of novel stable anisotropic single-layer crystals and a deeper understanding of their physical properties is very important. The understanding of their Raman spectrum is essential in distinguishing between the different structural phases and in determining the crystal orientation of the material. The present project puts forward a method to determine the crystal orientation of anisotropic materials through resonant Raman measurements from both first- and second-order Raman spectra. I will contribute to the study of first- and second-order resonant Raman scattering in anisotropic materials, from which information on the electron-phonon and exciton-phonon interactions can be obtained. These are very important for the understanding of light-matter interactions. Moreover, 2D materials are often subject to external forces such as strain and charge transfer to or from the substrate. Therefore, these effects on the physical properties of anisotropic materials will be thoroughly investigated.

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Research team(s)

Transition metal dichalcogenides as unique 2D platform for collective quantum behavior. 01/10/2018 - 30/09/2021

Abstract

Two-dimensional transition metal dichalcogenides (2D-TMDs) are atomically-thin materials at the forefront of research, owing to their special electronic and optical properties, their tunability by electric gating and mechanical strain, and easy heterostructuring. It is much less explored that they also exhibit a wealth of collective quantum phases, characterized by a collective behavior of the electrons that is entirely different from their individual states. One such phase is a charge density wave, where electrons at lower temperatures form an ordered quantum fluid that restructures the host material. Another low-temperature collective quantum phase in 2D-TMDs is a superconducting one, where electrons condense into a resistance-less sea of Cooper pairs, that carries electric current without dissipation. Furthermore, the spins of the electrons add to the combinatorial possibilities for novel quantum states, and can form textures in monolayer TMDs that are wholly absent in the bulk. All these states are strongly intertwined, but the fundamentals of their interplay are not well understood – which hinders further progress towards novel functionalities and advanced applications. In this project, I will elucidate this interplay using state-of-the-art theoretical tools, and provide a roadmap to tailor it – by e.g. strain, gating and doping – in order to establish 2D-TMDs as a unique platform for highly versatile quantum devices, employing the advantages of all different states at play.

Researcher(s)

Research team(s)

Advanced simulations of topological superconducting hybrids for the second quantum revolution 01/10/2018 - 30/09/2021

Abstract

The European Commission has just launched a €1 billion Flagship-scale initiative in Quantum Technology, within the European H2020 research and innovation framework programme. This initiative aims to place Europe at the forefront of the second quantum revolution, with quantum information, communication and computing at heart, as already unfolding in USA under push by Microsoft and Google. Both latter companies see superconducting hybrid devices as a base for viable quantum technology of the future. This project is aimed at positioning Flanders as a home for realistic theoretical simulations of such devices. At present, numerous experiments around the world are performed on superconducting hybrids with special topological properties, such that they may stabilize exotic Majorana fermions -a quasiparticle obeying non-Abelian statistics, thereby useful for fault-tolerant quantum computing. As no experimental setup is ideally perfect, the convincingly proven signature of the Majorana fermion is still missing. Furthermore, additional aspects appear that are not covered by simplistic models. Therefore, simulations based on realistic parametrizations and geometries are absolutely necessary for improving the theoretical understanding of ongoing experimental efforts, for convincingly confirming the detection and manipulation of Majorana, and to design quantum devices that can reliably replace current technology. The advanced simulations in this project are fully in service of that goal.

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Research team(s)

Atomically thin superconducting electronics – a multiscale approach. 01/01/2018 - 31/12/2021

Abstract

Superconducting electronics is crucial for a broad spectrum of applications, ranging from highly sensitive biomagnetic measurements of the human body to wideband satellite communications. The ever desired miniaturization and portability of such devices requires the fabrication and behavioral characterization of ultra-small superconducting circuits. Recent advances have enabled controllable growth of crystalline atomically thin (quasi 2D) superconductors, that harbor rich fundamental physics due to quantum confinement of both electrons and phonons, interaction with a substrate, non-trivial effects of strain and gating, etc., and thus hold promise for electronic, magnetic and optical properties that are otherwise unattainable. In other words, ultrathin superconductors can be the base for a new generation of ultra-low power and highly sensitive electronics, with more functionalities than the previous designs. The groundbreaking goal of this project is to enable the exploratory search for those functionalities, by developing multiscale simulations of atomically thin superconducting circuits - starting from ab initio information on electronic and vibronic changes at monolayer thicknesses, then revealing the role of the substrate, intercalants, electric gating, etc. on superconductivity in selected materials, towards simulations of nano-patterned micron-scale circuits, using advanced current-voltage-magnetic field characterization with ab initio parametrization.

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Research team(s)

The quest for the ground state of two-dimensional III-V semiconductors. 15/03/2017 - 14/03/2021

Abstract

The research on two-dimensional nanomaterials has grown exponentially after the experimental realization and characterization of graphene in 2005. Many new atom-thick material sheets have been theoretically proposed and experimentally realized since then and new possible structures are still predicted on a regular basis. To find new and possibly better materials for opto-electronics applications, it seems natural to investigate if 3D bulk materials that are already used for these applications can be scaled down to the 2D single layer limit, to even improve or tune their properties. This route has been followed for the group IV elements, leading to silicene, germanene, etc. Surprisingly, much less attention has been paid to the class of III-V materials, like InAs, GaAs, … Only the properties of these III-V compounds in the graphene-like (flat) or silicene-like structure (buckled) have thoroughly been investigated. However, it is well-known from molecular chemistry that group-III elements prefer planar sp2-bonded structures, as in trihydrides and trihalides, while group-V elements prefer tetragonal sp3-bonded configurations. It can be expected that these trends will pop-up again when reducing the 3D III-V bulk semiconductors to their 2D limit. The goal of this project is to identify the real ground state structures of 2D III-V compounds and to explore their electronic properties, using first-principles calculations. Another important field of research that arose from the research on graphene and graphene-like systems are topological insulators and the quantum spin Hall effect. The origin of this behavior lies in a band inversion, often realized by a strong spin-orbit coupling. So once we have determined the ground and metastable structures of the 2D compounds containing Tl and Bi, their topological character will be determined. The outstanding performance of many of today's opto-electronic devices is primarily due to the application of heterostructures, for example in lasers. Therefore it is also important to investigate the electronic properties of heterostructures composed of different 2D III-V semiconductors. Finally it is also natural to extend this research to the class of II-VI semiconductors.

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Research team(s)

Design of opto-electronic properties in two dimensional materials by enhanced flexoelectric coupling. 01/01/2017 - 31/12/2020

Abstract

Electromechanical effects, such as piezo- and flexoelectricity, are a consequence of the coupling of an applied electric field to the strain and the strain gradient, respectively. These effects are expected to be strongly enhanced in two dimensional materials (2D), first, due to the reduction in lattice symmetries in the 2D limit, and second, due to the superior elastic properties, allowing strains even up to 10% in some cases. Furthermore, 2D materials are fully flexible and bendable, thus ushering a new era of flexible opto-electronic devices. In this proposal, we will first investigate the fundamental flexoelectric properties of a wide variety of 2D materials by using a combination of analytical and ab-initio approaches. Important questions related to the magnitude of the coupling coefficients, the effect of phonon anharmonicity and the identification of materials with optimal electro- and mechanical properties will be answered. Subsequently we will model specific strain configurations as out-of-plane (ripples, folds, kirigami) and in-plane geometries (patterned layers, heterostructures, etc.). These are of significant importance because, as opposed to bulk electromechanical effects, modifications at the nanoscale in 2D materials greatly affect their optoelectronic properties. As concrete examples we will investigate the possibility of creating flexotransistors or flexo-photovoltaic devices.

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Research team(s)

Computational design of hetero-chiral magnonics. 01/01/2017 - 31/12/2020

Abstract

Magnetic heterostructures where the chiral interaction is spatially modulated will be investigated to see if they can be used to transport and process magnons. Similarly to photons, magnons are wavelike particles that can propagate through magnetic materials. This could lead to a completely new class of the information processing devices. Our approach will be based on of state-of-the-art numerical micromagnetic simulations on Graphical Processing Units (GPU's).

Researcher(s)

Research team(s)

Functional properties of two-dimensional nanostructured materials. 01/01/2016 - 31/12/2020

Abstract

With the proposed scientific research community involved research teams want to create the necessary critical mass to successfully combine self-organization and more generally surface modification for inducing improved as well as new functionalities with the ultimate aim to tune the electronic, magnetic and spintronic, mechanical, and optical properties. We want to achieve the following goals: • Understanding the influence of controlled surface modification on the functionalities and the applicability of 2D materials, including topological insulator surfaces. • Understanding the influence of contamination that can be present on the surface as well as at the interface with the substrate. • Exploring the modified and novel properties resulting from the low dimensionality, including quantum-mechanical effects. • A major strength of the proposed consortium is that there will be a very close interaction between the experimentally oriented research groups and the groups that focus on the theoretical modeling of the modified 2D materials.

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Research team(s)

Nano-materials. 01/01/2012 - 31/12/2020

Abstract

This project represents a research contract awarded by the University of Antwerp. The supervisor provides the Antwerp University research mentioned in the title of the project under the conditions stipulated by the university.

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Past projects

Data fusion model for cityflows. 01/10/2019 - 01/04/2020

Abstract

The University of Antwerp develops in this project in collaboration with IMEC a data fusion model for CityFlows, in which the density of motorized and non-motorized persons is obtained from the fusion of different data sources (including telco signalling data, Wifi scanning data, camera object detection, Telraam data, …).

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Research team(s)

Understanding and tuning of light matter interactions in transition metal dichalcogenides monolayers and their heterostructures (QuantumTMDs). 01/05/2019 - 30/04/2020

Abstract

Fundamental understanding and control of quantum phenomena on unprecedented length and time scales are essential for proper development of next generation devices. Recent advances in the synthesis of atomically thin layers of van der Waals solids such as graphene, boron nitride, and transition metal dichalcogenides (TMD) open up possibilities to success, for example, in computing, information and energy technology. Related to photonics and optoelectronics applications monolayer TMDs have potential for increasing the capabilities of conventional semiconductors by broad absorption spectrum, i.e., from near-infrared to the visible region. In this proposal, we will study the light matter interactions in monolayer TMDs and their heterostructures with emphasis on strong excitonic effects, and spin- and valley-dependent properties. To this end, we will develop model Hamiltonian techniques, which in conjunction with density functional theory based calculations will provide new insight in the light matter interactions in monolayer TMDs. The overarching goal of this proposal is to achieve understanding of novel quantum phenomena in monolayer TMDs in particular how heterostructuring, defects, and strain intertwine to produce interesting physical properties. The work proposed here will lead to major advances in understating how defects, heterostructuring, and strain modify the properties of 2D materials, resulting in novel quantum phenomena.

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Research team(s)

Tight-binding model and effective Hamiltonian for twodimensional materials. 01/03/2019 - 31/08/2019

Abstract

A wide range of two-dimensional (2D) materials ranging from graphene to topological insulators share the extraordinary phenomenon that electrons behave as relativistic particles in their low-energy excitations in different formats such as Dirac cones, Dirac nodal lines and Weyl nodes and so on. These emergent behaviors of fermions in condensed matter systems have attracted both experimental and theoretical researches. Density functional theory is a good point to start calculating the electronic properties of materials, but this method is unable to find all properties of the system. One of the most important methods to calculate the electronic properties of such systems is the Green's function approach. In this method the tight-binding (TB) model explains the physical system. Therefore we need to define a TB model and find the hopping coefficients between atoms and orbitals. With the linear combination of atomic orbitals (LCAO) method the system can be described by a set of non-interacting single-particles. By using the simplified LCAO method in combination with firstprinciples calculations, we are able to construct TB models in the two-centre approximation for 2D materials. The Slater and Koster (SK) approach is a powerful method to reproduce the first-principles data and construct the TB model. This method is applied to calculate the TB Hamiltonian of these systems based on the s, p and d orbitals. We obtain expressions for the Hamiltonian and overlap matrix elements between different orbitals for the different atoms and present the SK coefficients in a nonorthogonal basis set.

Researcher(s)

Research team(s)

Atomic collapse in Dirac-like materials. 01/10/2018 - 02/06/2020

Abstract

Soon after the formulation of the Dirac equation (1928), which describes relativistic particles, it was predicted that for a high charge Z of the nucleus the atom becomes unstable, leading to the phenomenon of atomic collapse. Because of the large required Z>170 value scientists were never able to verify it experimentally. However, the discovery of graphene and the fact that its charge carriers mimic relativistic (quasi-)particles opened up a new window on atomic collapse, which was recently observed experimentally in graphene. Using this recent observation as motivation, we will theoretically investigate the atomic collapse phenomenon in graphene and other Dirac-like materials having very different energy dispersions. We will study how the various differences between these materials influence the atomic collapse phenomenon and study how this phenomenon can be tuned by external electric and magnetic fields. The purpose of this proposal is two fold: 1) to study atomic collapse in different Dirac-like materials, which will give us fundamental information and understanding about atomic collapse at the relativistic level, and 2) to investigate the influence of atomic collapse on the transport of charge carriers in Dirac-like materials, providing us with very important information needed for the development of future applications .

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Research team(s)

Novel Magnetic Two-dimensional Materials. 01/10/2018 - 30/09/2019

Abstract

The scope of the proposed project is to investigate the magnetic properties of recently emerged two-dimensional (2D) materials having intrinsic magnetism. Nanoscale magnetism is of great scientific interest and has high technological relevance. Since the discovery of graphene, twodimensional materials have drawn considerable attention due to their extraordinary physical properties and potential application in nanoscale magneto-electronics, so-called spintronics. Although most of the 2D materials do not exhibit magnetism, the search for intrinsic ferromagnetism in the monolayer limit did not end. Motivated by the recent discovery of the ferromagnetic monolayer CrI3 and its number of layers dependent magnetic phase transitions we propose to use density functional theory to predict other 2D ferromagnetic materials. Furthermore, we want to understand the formation mechanisms and stability of magnetism in 2D materials and possible routes of tuning it by external stimuli such as strain, charge doping, and electric field.

Researcher(s)

Research team(s)

Moiré patterns induced in bilayer van der Waals heterostructures 01/10/2017 - 30/09/2020

Abstract

Two-dimensional (2D) materials are currently a very important topic in materials science due to their unique properties and high crystal quality. An important property of these materials is that they can be stacked on top of each other regardless of the mismatch between the unit cells and with almost any twist angle between the two lattices. This is thanks to the weak van der Waals interaction that acts between different layers. However, researchers have found that the properties of these stacked structures can be very different from its constituents, they not only dependent on the choice of 2D materials used for its construction but are also significantly influenced by the orientation of the two lattices. A difference in lattice constant and/or misorientation of the two lattices results in the appearance of a periodic superlattice structure called moiré pattern. Thus, the types of 2D materials used for stacking and the period of moiré pattern can be in principle used for the design of novel materials with desirable properties. In this project we will focus on the formation of moiré patterns as generated by stacking two monolayers on top of each other and their consequences on the different physical properties of the heterostructure. The effect of internal and external applied strain will be considered.

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Few-body correlation effects in transition metal dichalcogenide monolayers. 01/10/2017 - 30/09/2019

Abstract

Since the celebrated discovery of graphene, there has been a growing interest in two dimensional (2D) crystals for potential applications in next-generation nanoelectronic devices. Transition-metal dichalcogenides (TMDs) are a very promising class of materials that can be shaped into monolayers. Recently there has been increasing interest in these systems both theoretically and experimentally because of their particular properties. The strong Coulomb interaction in TMD monolayers makes these systems an excellent candidate for the study of different stronglycorrelated phases in 2D atomic crystals. The focus of this proposal is on excitonic effects in TMD mono- and multi-layers. I plan to investigate excitons, trions (charged excitons) and biexcitons. Recently, the stability and binding energy of these quasi-particles have been measured. The aim of my proposal is to numerically obtain the electronic and optical properties of excitons, trions and biexcitions in TMD layers and compare them with experimental data. The second part of the proposal deals with the study of excitonic superfluid properties in a system of double-TMD monolayers. I plan to show that coupled parallel TMD monolayers can be a very promising system for observing high-temperature superfluidity. This conviction is based on recent advances in fabricating TMD van der Waals heterostructures and the analogy of the system with double-bilayer graphene in which high-temperature superfluidity was predicted.

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Advanced electronic simulations of atomically thin superconducting films. 01/04/2017 - 31/03/2018

Abstract

Recent experiments show that electronic properties of atomically thin superconducting films are strongly influenced by atomic steps, primarily due to strongly altered electronic band structure and the phase coherence of the Cooper-paired electrons. In this project, we will describe and explain these effects using state-of-the-art Bogoliubov-de Gennes numerical simulations. This challenging study will provide the missing ingredient for deep theoretical understanding of possible electronic states and transport features in atomically thin films, and provide explanation and guidance for ongoing scanning tunneling microscopy (STM) experiments worldwide.

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Spin-wave-like excitations in low-dimensional ferromagnets. 01/10/2016 - 30/09/2020

Abstract

Today, information in logic applications is mostly carried by the electric current of electrons and holes in semiconductors. There is however a rapidly growing interest in the transmission of information encoded by electron and atomic spins which, in principle, can be realized by the propagation of spin-waves or magnetization waves through low-dimensional ferromagnets. Genuine spin waves originate from deviations of individual, single spins with respect to the perfectly ordered ground state of a ferromagnet in which all spins are aligned parallel to each other. The waves that are propagating such deviations through the lattice of the ferromagnet are called spin waves and, as such, they can be excited only at very low temperatures. However, at room temperature one may excite similar waves, corresponding to the spatial variation of the macroscopic magnetization vector that locally deviates from the spontaneous magnetization. Although the basic quantum theory of ferromagnetism has been established already in the previous century, various fundamental problems are left unsolved or remain to be highly controversial, especially those concerning low-dimensional magnets. Rather than relying on semi-classical theories and simulation programs, the research of this PhD will focus on the fundamental physics of both the equilibrium properties and the spin dynamics of one- or two-dimensional ferromagnets, all to be studied in the framework of quantumstatistical and condensed matter physics

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Investigation of prototype devices in two-dimensional materials. 01/10/2016 - 30/09/2019

Abstract

The exploration of novel low dimensional atomically thin materials is very important for a future generation of flexible nanoelectronics, optoelectronics, and energy storage devices. Among these, graphene has demonstrated a wide range of properties including, high electrical and thermal conductivity, and optical transparency. Due to the semiconducting nature of transition metal dichalcogenides, they are also becoming promising candidates. More recently, high frequency devices containing few layer black phosphorous have been demonstrated. Combining these materials in heterostructures would lead to a many-fold enhancement in their functionalities. In this proposal, with the combined effort of the two teams, prototype devices containing 2D heterostructures will be investigated. A deep understanding of the stability and electronic properties of heterostructures, investigated by the Chinese team with the use of ab-inito simulations will be coupled to effective models of prototype devices, either at tight binding or continuum level, led by the Belgian team. Systems comprised of vertical and in-plane heterostructures will be used to propose candidate devices taking advantage of either the charge or spin degrees of freedom. Of special interest are also tunable opto-electronic and excitonic effects. It is expected that this collaborative effort will lead to both a fundamental understanding of optoelectronic processes and the modeling of specific nano- and microelectronic devices.

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Exploring the frontiers of optics of Dirac materials. 01/10/2016 - 30/09/2019

Abstract

This proposal aims at exploring the frontiers of the optics of Dirac materials. By modelling how light interacts with two and three dimensional Dirac materials, we want to access the peculiar world of electrons with very unconventional properties. We will image how the sea of electrons reacts to an external light source. On the one hand, we want to use this light source to measure how viscous the sea of electrons is. For example, whether it is more like honey, a viscous fluid, or more like water, a less viscous fluid. On the other hand, we will put forward proposals to extend the lifetime of plasmons in Dirac materials. Plasmons can be thought of as a wave in the sea of electrons. In this wave the electrons and the incident light are coupled with each other and move around coherently. It is possible to manipulate these plasmons in order to guide light in the direction you want and use them for photonic applications. However, it remains a challenge to find systems in which the plasmons live long enough to be useful. Therefore, we will investigate whether it is possible to take advantage of particular properties of the crystal or external electric currents to make the plasmons more robust and extend their lifetime. The proposed work will be done in close collaboration with several foreign experimental groups that will provide the necessary feedback to improve our models and to verify the proposed physics.

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Research in the field of condensed matter theory. 01/10/2016 - 30/09/2017

Abstract

Objectives of the sabbatical year: - Defining new innovative lines of research for my research group - Recharging - Develop new collaborations with mainly experimental groups - Strengthen existing partnerships

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Nanostructured graphene. 01/09/2016 - 28/02/2017

Abstract

Study of energy levels in graphene nanostructures. The confined states in three different graphene systems were considered: 1) monolayer-bilayer graphene quantum dots (QDs), 2) trilayer graphene QDs, and 3) hybrid monolayer-bilayer interfaces. As a new project, we investigate the existence of confined massless fermion states in a graphene quantum well by means of analytical and numerical calculations. Our proposal is based on the fact that the transmission coefficient through both barriers and wells in graphene displays a strong angular dependence. The trigonal warping effect can suppress this tunneling and thus allow the confinement of electrons. We also propose to calculate electrical conductivity along the quantum well direction. We will investigate if there is any dependence of the electrical conductivity on the specific direction of the quantum well with respect to the graphene lattice. The idea is that this would lead to the realization of a novel type of graphene wire where conduction is not influenced by the boundaries. The aim of our project is to guide experimental research towards confinement of carriers in graphene nanostructures.

Researcher(s)

Research team(s)

Transition metal dichalcogenides heterostructures 01/04/2016 - 15/08/2016

Abstract

The main focus of this project is to understand the physical properties of transition metal dichalcogenides monolayers and their heterostructures. Motivated by recent advances in experimental techniques that have made it possible to use these nanoscale materials in electronic and optoelectronic applications, the following important questions will be investigated within this research proposal by using state-of-the-art computation methods: 1) Which materials and/or contact architectures should be used in order to realize zero-resistance contacts for optoelectronic and nanoelectronic devices based on TMDs? 2) How do physical properties of TMD based quantum dots depend on shape and size?

Researcher(s)

Research team(s)

Novel two dimensional atomic crystals 01/04/2016 - 30/04/2016

Abstract

Thanks to advances in experimental techniques, 2D crystals other then graphene-like and transition-metal dichalcogenides (TMDs) have been very recently introduced such as monolayer alkaline-earth-metal hydroxides (AEMHs) and post-transition metal chalcogenides (PTMCs) which are expected to have novel physical properties. The aim of this project is to predict novel AEMHs and PTMCs monolayers and to investigate the stability and the electronic, magnetic and optical properties of these new type of 2D crystals.

Researcher(s)

Research team(s)

Theoretical investigation of electronic transport in functionalized 2D transition metal dichalcogenides (Trans2DTMD). 01/01/2016 - 31/12/2018

Abstract

Metallic transition metal dichalcogenide (TMD) monolayers are promising ultrathin materials which have the potential to complete the range of graphene-related materials by offering tunable metallic phases with strong spin-orbit coupling. Many of them can be achieved by small structural deformations and doping of Group 6 TMDs and thus could thus be used as electrode materials within a single monolayer, resulting in a very low contact resistance. Experimental study of metallic TMDs is difficult as these phases are often metastable or rely on very subtle structural modifications. Thus, a careful theoretical investigation is imperative before complex experimental studies should be pursued. This consortium will investigate metallic TMD structures, including intrinsically metallic phases, metastable metallic phases, and external factors to trigger semiconductor-metal transitions such as doping, defects and strain. Special attention will be given to spin-orbit splitting and ways to control them. Computer simulations will range from band-structure calculations of small unit cells to rather complex systems, including heterostructures, doped and defected systems up to grain boundaries. Conclusions on the suitability of these materials in practical application will be further confirmed by explicit transport calculations and device simulations. While most calculations can be carried out using state-of-the-art software, some method developments are necessary and will be carried out here. Numerical methods that scale linearly with the system size, O(N), will be developed by using a polynomial expansion of the components of the conductivity tensor. These will allow for simulations of large unit cells in the presence of disorder and the calculation of spin- and valley- dependent contributions. It will become therefore suitable to describe the Spin and Valley Hall effects in realistic models of TMDs.

Researcher(s)

Research team(s)

Two-dimensional atomic crystals as building blocks of new heterostructures. 01/10/2015 - 30/09/2018

Abstract

Nanotechnology is an emerging multidisciplinary field that is revolutionizing materials science and optoelectronics. Since the future of this new technology will be shaped by the accessible materials, searching for new materials with novel functionalities will be crucial. The present proposal aims to make significant contributions to the engineering of heterostructures composed of atomically-thin crystal structures. Currently, the research on atomic-scale heterostructures is in its earliest stage and the number of available materials is rather limited. The stability and electronic properties of novel atomically-thin crystal structures will be investigated using state-of-the-art computational techniques. Density Functional Theory, will be used by the applicant, which is a quite powerful tool used in condensed matter physics, chemistry and biophysics to investigate the electronic and magnetic properties of many-body systems. In the second part, monolayer crystal structures that have desired properties will be used as building blocks of nanoscale heterostructures. The possibility of using such heterostructures in various optoelectronic devices such as Schottky diodes, PN junctions and spin-valves will be examined.

Researcher(s)

Research team(s)

Novel electronic properties of atomically-engineered ultra-thin superconducting films and their emerging topological states. 01/10/2015 - 30/09/2018

Abstract

Due to their impact on fundamental physics and possible applications in low-power electronics, superconducting ultra-thin films with thickness ranging from one to a few atomic layers have recently attracted tremendous interest. Their superconducting properties are strongly influenced by the thickness, geometry and structure of the film due to the quantum confinement effects on atomistic scale. Since last years, such ultra-thin films can be grown experimentally, in clean crystalline form, and tuned with atomic precision. Numerous novel electronic properties were observed and even prototype field-effect transistors were realized. However, most of the novel properties are not precisely understood from theoretical standpoint. In this project, we will therefore study the effects of atomic engineering by state-of-the-art Bogoliubov-de Gennes numerical simulations of ultrathin superconductors, with the hope to reveal the impact of atomic edge steps, disorder, and substrate choices on the superconducting condensate and its electronic structure. Emerging new topological states (including vortices, fractional vortices, and skyrmions) will be considered in the presence of magnetic field and electric current. This project will ultimately provide a comprehensive review of possible properties and how to achieve them in scanning tunneling microscope (STM) experiments on these fascinating materials.

Researcher(s)

Research team(s)

Few-body correlation effects in transition metal dichalcogenide monolayers. 01/10/2015 - 30/09/2017

Abstract

Since the celebrated discovery of graphene, there has been a growing interest in two dimensional (2D) crystals for potential applications in next-generation nanoelectronic devices. Transition-metal dichalcogenides (TMDs) are a very promising class of materials that can be shaped into monolayers. Recently there has been increasing interest in these systems both theoretically and experimentally because of their particular properties. The strong Coulomb interaction in TMD monolayers makes these systems an excellent candidate for the study of different stronglycorrelated phases in 2D atomic crystals. The focus of this proposal is on excitonic effects in TMD mono- and multi-layers. I plan to investigate excitons, trions (charged excitons) and biexcitons. Recently, the stability and binding energy of these quasi-particles have been measured. The aim of my proposal is to numerically obtain the electronic and optical properties of excitons, trions and biexcitions in TMD layers and compare them with experimental data. The second part of the proposal deals with the study of excitonic superfluid properties in a system of double-TMD monolayers. I plan to show that coupled parallel TMD monolayers can be a very promising system for observing high-temperature superfluidity. This conviction is based on recent advances in fabricating TMD van der Waals heterostructures and the analogy of the system with double-bilayer graphene in which high-temperature superfluidity was predicted.

Researcher(s)

Research team(s)

Transport properties of graphene van der Waals structures 01/02/2015 - 31/12/2015

Abstract

The transport properties of graphene on boron-nitride or on other graphene layers are strongly modified due to an induced periodic potential. Because of a weak inter-layer coupling (van der Waals), the relative mismatch becomes an important tuning parameter. We will numerically investigate the influence of substrate strain and rotation on transport. This study will provide a theoretical understanding of recent experiments by the Manchester group.

Researcher(s)

Research team(s)

Enhanced electron-hole superfluidity in double graphene nanoribbons. 01/02/2015 - 31/12/2015

Abstract

We propose two coupled electron-hole quasi one dimensional (1D) graphene nanoribbons as a new nanostructure to observe superfluidity at enhanced superfluid parameters. The aim of our project is to investigate the superfluid state properties of double armchair graphene nanoribbon (GNR) devices in order to guide experimental research and realization of high-Tc electron-hole superfluidity.

Researcher(s)

Research team(s)

Exploring mechanical properties of pristine graphene and with nanoparticles using stochastic physics 01/02/2015 - 31/10/2015

Abstract

In this project through a powerful combination of detailed theoretical predictions and atomic-scale characterization, we propose to connect scanning tunneling microscopy data (provided by experimentalists of the University of Arkansas, USA) to stochastic physics and membrane theory, and discover basic and advanced mechanisms for controlling the strain distribution in freestanding graphene.

Researcher(s)

Research team(s)

Many-body physics of coupled graphene multilayers. 01/01/2015 - 31/12/2018

Abstract

The key questions we plan to answer are: - How many graphene layers are needed in order to make quantum Wigner crystallization possible? - Which crystal phases are possible and what is the phase diagram (and its dependence on the different tuning parameters)? - What is the effect of the dielectric environment on excitonic superfluidity in spatially separated electron hole layers of few layer graphene? - How does the critical temperature depend on the number of graphene layers in each sheet and on the carrier density (and on the other tuning parameters)?

Researcher(s)

Research team(s)

Ab initio study of the band-lineup problem in twodimensional systems. 01/10/2014 - 30/09/2017

Abstract

In this project, we propose to investigate the electronic properties of two-dimensional (2D) heterostructures. Heterostructures can be defined as the combination of different materials into a single structure in which the various materials maintain their general characteristics. Another useful term is that of a heterojunction which can be regarded as the interface between two solid-state materials. Heterostructures are of both technological and fundamental interest. The technological importance is easily acknowledged in such fields as solid-state electronics and optoelectronics, but they are also of profound fundamental interest for materials science.

Researcher(s)

Research team(s)

(Topological) superconductivity in atomically thin metals 01/10/2014 - 31/10/2016

Abstract

Since the "Graphene Revolution", much progress has been made in fabrication and understanding of one-monolayer-thick two dimensional crystals. Until recently, it was believed superconductivity - the property exhibited by some materials where below a certain temperature, all electrical resistance is lost - could not exist in such systems. When superconductivity was experimentally observed in a monolayer of Pb deposited on a Si substrate, it triggered a debate on the exact origin of this phenomenon. In parallel, tin (Sn), apart from being an elemental superconductor, was found to be a topological insulator in the 2D limit (dubbed "stanene" in analogy to graphene), with ability to conduct electricity perfectly on the edges, while remaining insulating in the interior. This edge superconductivity is extremely robust against impurities or thermal fluctuations, making stanene one of the prime candidates for advanced technological applications. This is the setting in which the proposed research on "topological superconductivity" will take place. We aim to study the behaviour of several different metals in the two dimensional limit: first a single atomic layer, then increasing the number of layers one at a time, and analyze the electronic and phonon spectra using state-of-the-art numerical techniques. This will give access to the topological nature of the electrons, as well as shed light on the reasons of nucleation and pathways of evolution of superconductivity, in a close relationship with available experiments. Given the impact that both superconductivity and topological insulators have had on research so far, the fundamental and technological relevance of this research can hardly be overstated.

Researcher(s)

Research team(s)

Nanostructured topological insulators. 01/10/2014 - 30/09/2016

Abstract

The route we propose is by nanostructuring TIs. For example, in this project we study by ab initio density functional theory calculations thin slabs of TIs, and their interaction with normal insulating layers, and the effect of the adsorption of atoms on the surface of a TI on its surface electronic structure. Also the influence of magnetic impurities is of great importance, as they will destroy the topological surface states. Another class of nanostructured TIs are cylindrical nanowire TIs which are expected to show a rich surface electronic structure.

Researcher(s)

Research team(s)

Many-body effects in single- and multi-layers of graphene. 01/10/2014 - 30/09/2016

Abstract

This proposal aims to explore novel effects induced by electron-electron interaction, with or without magnetic fields, in graphene and multi-layer graphene. Investigation of plasmons in such systems and in related 2D atomic crystals.

Researcher(s)

Research team(s)

Multiscale in Silico Study of Multiband Superconductors. 01/10/2014 - 30/09/2015

Abstract

One Fe-based superconductor that attracted a lot of attention recently is FeSe. The growing evidence suggests that monolayer FeSe superconducts up to 65 K and may become an ideal model system for testing several theoretical ideas [He13,Tan13]. Latter references show the importance of the substrate as a source of strain in the superconducting properties. Intriguingly, monolayer FeSe displays an important feature common to many superconductors: an inflection in the band structure (i.e. small or zero Fermi velocities) at energies that fall within the gap that opens below the critical temperature. This indicates again that a detailed knowledge of the electronic structure is a prerequisite for a successful theory

Researcher(s)

Research team(s)

Modulating the electronic structure of two-dimensional heterostructures. 01/10/2014 - 30/09/2015

Abstract

Since the discovery of graphene, two-dimensional (2D) materials have attracted great attention mainly due to their unique physical properties and capability to fulfill the demands of future nanoelectronic industry on flexibility. Up to now various 2D monolayers have been synthesized experimentally, and they show many interesting features which are promising for technological applications such as field effect transistors, solar cells, and light emitting diodes. Combing different 2D materials into a single structure results in 2D heterostructures. 2D heterostrutures can have new properties different from the constituents, allowing the development of new devices in spintronics, optoelectronics and solar energy conversion. To achieve realistic applications, understanding and manipulating the electronic properties of 2D heterostructures is of importance. In this project, we investigate the effects of different factors, such as interface, composition of different materials and strain, on the properties of silicene/silicane superlattices and MX2 heterostructures. The aim is to provide theoretical guidance to tune the electronic and magnetic properties of 2D heterostructures.

Researcher(s)

Research team(s)

Phase Transitions in Ultra-thin Crystal Structures 01/02/2014 - 31/12/2014

Abstract

In the field of condensed matter physics, the materials receiving the most attention today are Transition Metal Dichalcogenides (TMDs). Although bulk TMDs have been investigated for long time, recent advances in experimental techniques revealed many unique properties of single layers of TMDs. The scope of the present project is the investigation of possible phase transitions in few-layer and monolayer TMDs.

Researcher(s)

Research team(s)

Synthesis, properties and modeling of doped ZnO nanowires and nanocrystals. 01/01/2014 - 31/12/2017

Abstract

In this project, we will investigate the influence of different defects on the doping efficiency of ZnO nanowires (NWs) and nanocrystals (NCs), paying specific attention to the reliable p-type doping. On the other hand, we will explore the influence of the nanometer size dimensions on the electronic properties.

Researcher(s)

Research team(s)

Superconductivity per atomic layer. 01/01/2014 - 31/12/2017

Abstract

In this project, we will obtain theoretical insight in the effect of confinement and the choice of the substrate on the superconducting properties of atomistically thin films – by adding one monolayer at the time. Research will be performed via ab initio studies of the structural, electronic, and vibrational properties of few‐monolayer films, and the application of Bogoliubov‐de Gennes and Eliashberg formalisms to study the superconducting properties of these films, based on the input from the ab initio calculations.

Researcher(s)

Research team(s)

First-principles positron spectroscopy of topological insulators. 01/01/2014 - 31/12/2017

Abstract

In this project we will build on the well developed ab intio techniques for the study of positrons in bulk solids and on previous models to provide an ab initio theory of positron surfaces states. We will apply this theory to study the interaction of positrons with topological insulator surfaces.

Researcher(s)

Research team(s)

Spintronics with Transition metal Dichalcogenides. 01/01/2014 - 31/12/2014

Abstract

One of the aims of this project is to study possible implementations of the TMDs to the field of spintronics. The optimal single atomic layer TMD compounds for spintronics purposes will be searched. Next research topic in this project is to investigate TMDs based heterostructures.

Researcher(s)

Research team(s)

Electron correlations in bilayer and trilayer graphene. 01/10/2013 - 30/09/2016

Abstract

Many-body effects in multilayers of graphene and in coupled multilayers of graphene. Exciton superfluidity will be investigated in two coupled multilayers of graphene. The possibility of Wigner crystallization in such graphene layers will studied.

Researcher(s)

Research team(s)

Functionalization of graphene. 01/10/2013 - 13/07/2016

Abstract

This project represents a formal research agreement between UA and on the other hand Erasmus Mundus. UA provides Erasmus Mundus research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Superconductivity per atomic layer. 01/10/2013 - 30/09/2014

Abstract

In this project, we want to get theoretical insight in the effect of confinement and the choice of the substrate on the superconducting properties of atomically thin films by adding one monolayer at the time. In this respect, we aim to study elementary superconductors such as Pb and Sn, but also layered chalcogenides (such as NbSe2), and borides (MgB2, OsB2). The latter are particularly important being the most recently discovered (where MgB2 is the highest-temperature conventional (BCS theory) superconductor), while also being two-gap superconductors – where subtle interplay of two coupled Cooper-pair condensates leads to very rich physics.

Researcher(s)

Research team(s)

Chiral states of bilayer graphene in the presence of Rashba and intrinsic spin-orbit couplings. 01/10/2013 - 30/09/2014

Abstract

The aim of this project is to realize an analytically solvable model by deriving an effective Hamiltonian for the low-energy states of a BLG. We will assume that the system is in teh ballistic regime and will use the famous Landauer-Büttiker formula to study the charge and spin-dependent transport. In order to solve the effective Hamiltonian, at first we will look for an analytic solution. Subsequently, we will switch to find a numerical solution by using methods based on finite-difference of finite-elements; i.e., when we consider more complicated potential profiles. In this case we will employ a numerical solver such as COMSOL or MATLAB. Alternatively, we will write the Hamiltonian within a tightbindind model and use subsequently an exact numerical diagonalization approach.

Researcher(s)

Research team(s)

Numerical experimentation on new superconducting materials. 15/09/2013 - 14/07/2016

Abstract

This project represents a formal research agreement between UA and on the other hand Erasmus Mundus. UA provides Erasmus Mundus research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Self-Assembly of Patchy Particles for Nanotechnology Applications. 01/09/2013 - 31/08/2016

Abstract

We will build on our previous joint research on classical many-particle systems. Two fundamental extensions will be required in order to describe these novel systems: 1) the isotropic inter-particle interaction will now be generalized to anisotropic one with anisotropic particles. This implies that each particle will not only be characterized by its position but now also its orientation will be important resulting in a substantial increase of the degrees of freedom. 2) The hydrodynamic interaction with the fluidic environment will be incorporated increasing the complexity of the problem (and the computational challenges).

Researcher(s)

Research team(s)

Novel confinement-induced phenomena in superconducting nanograins. 01/09/2013 - 31/08/2015

Abstract

This project represents a formal research agreement between UA and on the other hand the Federal Public Service. UA provides the Federal Public Service research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Mechanical properties and chemical bonding at the interfaces in polymer-based composite materials (InterPoCo). 01/03/2013 - 28/02/2017

Abstract

The main goals of the SB01 project "Mechanical properties and chemical bonding at the interfaces in polymer-based composite materiais" (InterPoCo) within the H-INT-S program are to (i) develop and apply a set of experimental and computational tools for comprehensive structural, compositional and quantitative mechanical characterisation of the interfaces in polymer-based composites at na no- and microscale level, (ii) to measure and predict structural, electronical, compositional, thermodynamica I and mechanical properties of bulk polymers and interfaces in polymer-based composites, (iii) to validate and improve the prediction reliability by emphasizing the interplay between modelling and experimental data obtained using a high-throughput approach and advanced characterisation results and (iv) to provide currently unavailable information on the above aspects to the running and future vertical SIBO programs.

Researcher(s)

Research team(s)

Theoretical study of lattice thermal properties of fluorinated graphene. 01/02/2013 - 31/12/2013

Abstract

Using large scale atomistic simulations with the reactive force field approach (ReaxFF) we will investigate the lattice thermal properties of fluorinated graphene (FG). We will study the effects of defects on the lattice thermal properties of FG, e.g. lattice constants, rippling behavior, etc. The aim is to explain the recent experimental measurements of the lattice thermal properties of both fully and partially covered sheet of graphene by F atoms.

Researcher(s)

Research team(s)

Vibrational and electronic properties of superconducting films and nanoparticles investigated by advanced synchrotron and theoretical methods. 01/01/2013 - 31/12/2016

Abstract

In this project we aim to get a deeper understanding of the intimate link between the overall superconducting properties on one hand and the lattice dynamics of nanoscale systems on the other hand. We will approach this problem via new theoretical routes in conjunction with state of the art experiments.

Researcher(s)

Research team(s)

Strain engineering of electronic correlations in graphene. 01/01/2013 - 31/12/2016

Abstract

The key questions we plan to answer in this project are: - How does strain affect electronic correlations? - Can one mechanically induce or manipulate magnetism in graphene? - Can different correlated states be stabilized through strain engineering?

Researcher(s)

Research team(s)

A quantum solver for junctionless III-V quantum devices. 01/10/2012 - 30/09/2016

Abstract

The aim of the PhD is to construct a quantum solver for investigating transport in highmobility two(three)-dimensional electron gases residing in the active areas of junctionless III-V structures and devices. A substantial effort will go into the numerical implementation of the quantum transport equation - e.g. the Wigner-Liouville equation - describing the steering quantum effects in the transport direction, the Schrödinger equation accounting for lateral quantum confinement, Poisson's equation fixing the local electrostatic potential and the constitutive equations yielding the densities and invoking a fully self-consistent coupling between all equations.

Researcher(s)

Research team(s)

Theoretical study of fluctuations in unconventional superconductors. 01/10/2012 - 30/09/2015

Abstract

One of the main objectives is to develop efficient Monte Carlo methods, which can rigorously describe thermal (classical) phase fluctuations in unconventional superconductors. Although the core of these methods is generic, we will develop specific formulations for the different symmetries of the superconducting order parameters.

Researcher(s)

Research team(s)

Investigation of Novel Graphene-like Structures. 01/10/2012 - 30/09/2015

Abstract

The main objective of my project is to reveal electronic and magnetic properties of nanosized flat materials. The subject materials of the project are graphene and graphene-like structures. Graphene is made of carbon atoms that are one of the most abundant elements in the earth crust and it was shown earlier that it has many unique properties. Moreover graphene based materials are cheap and easier to integrate to existing technological applications. The results obtained in the scope of this project will be beneficial for future device applications. The developments of effective electronic device components, that are suitable for low-resistance and high mobility transport, are priorities in nanoelectronics research. I aim to extend the twodimensional playground created by graphene into a broader set of materials and discover new structures having new functionalities. Both in terms of theoretical and technological gain, the proposed work is very timely and relevant to today's science.

Researcher(s)

Research team(s)

The effect of strain on spin-orbit coupling in single- and multi-layer graphene. 01/10/2012 - 10/04/2015

Abstract

In this project we will investigate the spin-orbit interaction in graphene in the presence of in-plane and out-of-plane strain. By applying strain the interatomic distance changes and a rehybridization between different orbitals occurs. The key question which I want to answer is: how is the intrinsic and extrinsic spin-orbit coupling modified in the presence of strain? Therefore we will derive a modified Hamiltonian with spatial dependent spin orbit coupling. We will use this effective Hamiltonian to investigate several problems such as the quantum Hall states and edge states, spin polarization, quasi-bound states, topological insulator behaviour, valley and spin filtering. Such theoretical studies are important to complement and guide experimental work. The outcome of the present study will be different proposals how to manipulate in a controllable way (e. g. through strain) the spin-orbit interaction in single and multilayer graphene based systems.

Researcher(s)

Research team(s)

Ab initio study of nanostructured topological insulators. 01/10/2012 - 30/09/2014

Abstract

The route we propose is by nanostructuring TIs. For example, in this project we study by ab initio density functional theory calculations thin slabs of TIs, and their interaction with normal insulating layers, and the effect of the adsorption of atoms on the surface of a TI on its surface electronic structure. Also the influence of magnetic impurities is of great importance, as they will destroy the topological surface states. Another class of nanostructured TIs are cylindrical nanowire TIs which are expected to show a rich surface electronic structure.

Researcher(s)

Research team(s)

Frustration in Multiband Superconductors. 01/10/2012 - 04/08/2013

Abstract

This project represents a research contract awarded by the University of Antwerp. The supervisor provides the Antwerp University research mentioned in the title of the project under the conditions stipulated by the university.

Researcher(s)

Research team(s)

Junctionless III-V quantum devices new concepts and transport properties. 01/07/2012 - 30/06/2016

Abstract

The aim of the project is to investigate quantitatively the potential and perspective of a class of newly proposed semiconductor device concepts based on the geometry and architecture of the junctionless IlI-V nanowire transistor. Moreover, a common feature to be shared by all concepts is the requirement that quantum mechanics be a crucial part of the working principle that governs the active device areas.

Researcher(s)

Research team(s)

Tuning of the mechanical and electronic properties of graphene by strain, chemical doping and defects (MESCD). 01/07/2012 - 30/06/2014

Abstract

In this project we intend to focus on basic and advanced mechanisms that are potentially useful for controlling i) the strain distribution, ii) the band gap, iii) the observation and visualization of electronic polarization in single/multilayer graphene at the atomic scale.

Researcher(s)

Research team(s)

Computational modeling of materials (FWO Vis. Fel., Hasan SAHIN, Turky). 02/01/2012 - 31/12/2012

Abstract

Recent developments in synthesis and characterization of nanoscale materials have motivated theoretical work in exploring quantum effects at the nano-level. The aim of the project is to conduct theoretical research in order to identify and understand the fundamental physical mechanisms underlying the surface, interface and transport behavior of a variety of nanoscale materials using computational methods.

Researcher(s)

Research team(s)

Self-assembly of colloids with directional interaction. 01/01/2012 - 31/12/2015

Abstract

We plan to study the self-assembly of colloidal particles with directional interactions, i.e., Janus spheres and lock-and-key colloids, and address the kinetic growth of clusters, the influence of fluctuating membranes. Different aggregates will be investigated depending on the size of particles, the interaction strength, the number of species, etc.

Researcher(s)

Research team(s)

Interplay between atomic layers and functional adsorbates. 01/01/2012 - 31/12/2015

Abstract

Graphene is a non-magnetic, two-dimensional semimetal, which can be turned into an n- or p-type conductor by gate voltages. This results in unusually high charge carrier mobilities with mean free paths of several microns. The carriers follow a linear dispersion relation where the energy is proportional to the wave number, a behavior that is expected for massless particles. Within this project, we consider graphene in an electronic- and magnetic sense as a 'blank page', which will be modified by introducing defects, by adsorbed/implanted gas- or metal atoms, and by covalently bound atoms and chemical groups. We will monitor the evolution of the band-structure related, electronic and magnetic properties as a function of the type and density of these modifications. Hereby, theoretical modeling based on ab initio calculations and experimental analyses (conductivity, scanning probe microscopy in various forms, photocurrent spectroscopy) will go hand in hand. Special emphasis goes to the quest whether it is possible to achieve an 'engineered' band gap via targeted modifications: this would open broad applications from nanoelectronics to (bio-)chemical sensors. Analysis of deliberately induced defects includes also the mutual ordering of defects and the orientational ordering of adsorbants with respect to the underlying graphene layer.

Researcher(s)

Research team(s)

Accelerated numerical methods for graphics processors applied to inhomogeneous graphene. 01/01/2012 - 31/12/2014

Abstract

We will study two peculiar configurations of graphene sheets, both involving broken translational symmetry: nano-pore graphene, a mesh of interconnected graphene ribbons which shows great potential in spintronics applications due to the appearance of edge magnetism; inhomogeneous strain in multilayer graphene for which pseudo-magnetic fields and pseudo-Landau levels are predicted and will greatly influence the electronic properties of the material. We will develop efficient numerical codes running on clusters of graphical processing units (GPUs).

Researcher(s)

Research team(s)

Josephson coupled superconducting multi-layers as tunable metamaterials 01/01/2012 - 31/12/2012

Abstract

This project is devoted to a study of high-frequency electromagnetic field propagation in layered superconductors, which can be considered as superconducting metamaterials due to anisotropic dielectric properties. In addition to their low loss, compact strcture and nonlinear properties, these structures present unprecedented level of controllability for the propagation of electromagnetic waves, which are not available in standard materials. Quantum metamaterials are also considered in an example of a chain of identical superconducting charge qubits inside a superconducting resonator. In such a medium the coherent quantum dynamics of qubits determine the properties of the system, leading to interesting physical processes.

Researcher(s)

Research team(s)

Research in the field of theoretical studies of nanostructured superconductors. 15/11/2011 - 31/12/2012

Abstract

The research in the field of theoretical studies of nanostructured superconductors is devoted to the theoretical treatment of vortex matter in nanostructured low Tc superconductors and superconductor/ferromagnet heterostructures.

Researcher(s)

Research team(s)

Electronic structure of modified graphene. 01/10/2011 - 30/09/2014

Abstract

The project deals with the theoretical characterization of functionalized graphene. Graphene is a recently (2004) discovered material with extraordinary electronic and mechanical properties. For some applications of graphene in nanothechnology it is important to change its properties. E.g. there is a problem for using graphene as the channel material in transistors because the conductivity of graphene always remains finite, i.e. the transistor can not be switched off. This problem can be overcome by functionalizing graphene, i.e. by the chemical attachment of atoms and molecules on a graphene surface. But functionalization is also important for other applications in e.g. biotechnology and spintronics. In this project I plan to investigate this functionalization by simulating it on an atomic level with theoretical models and examining the resulting changes in the electronic and mechanical properties.

Researcher(s)

Research team(s)

Interactions in composite graphene-based electronic systems. 01/10/2011 - 30/09/2012

Abstract

We focus on the analytical description of interacting electrons in novel quasi-onedimensional graphene-based systems: partially unzipped nanotubes and quantum spin Hall (QSH) edge states. Unlike their higher-dimensional counterparts, such systems often display Luttinger-liquid instead of Fermi-liquid behaviour, i.e. the fundamental excitations are not individual quasi-particles, but density waves that each can carry charge or spin.

Researcher(s)

Research team(s)

Electronic and structural properties of complex oxide multilayer systems at the atomic scale: a (S)TEM and EELS investigation. 01/10/2011 - 30/06/2012

Abstract

During this project novel oxide materials (layered systems) will be characterized to provide insight in their macroscopic properties. The techniques used, (scanning) transmission electron microscopy (S/TEM) and electron energy loss spectroscopy (EELS), will provide chemical and structural information down to the atomic scale due to the improved resolution of the QU-Ant-EM microscope. Several data analysis techniques will be compared and adapted in order to maximize the output of information obtained in these experiments.

Researcher(s)

Research team(s)

Visiting Postdoctoral Fellowship (Project 'Nanostructured and nonhomogeneous quantum wires'.)(BUDAGOSKY MARCILLA, Jorge Alejandro Marcilla, Spain) 01/05/2011 - 30/04/2012

Abstract

The aim of the project is to investigate theoretically the optical properties of GaN/InGaN core-shell nanowire structures. First the strain fields will be calculated including the piezoelectric potential. In the next step the electronic structure will be calculated by using the effective mass k.p-theory. The obtained band structure will be used to obtain the optical properties, i.e. optical absorption and excitonic effects.

Researcher(s)

Research team(s)

Electrical transport in nanostructures. 01/03/2011 - 31/08/2012

Abstract

This project represents a formal research agreement between UA and on the other hand the Federal Public Service. UA provides the Federal Public Service research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Vortex matter in type-1.5 superconductors. 01/01/2011 - 31/12/2014

Abstract

The project will investigate experimentally and theoretically the properties of the vortex matter in type-1.5 superconductors and the conditions for the realization of type-1.5 superconductivity in different materials.

Researcher(s)

Research team(s)

Nanoscale superconductivity: coherence and robustness of the superconducting state due to quantum confinement. 01/01/2011 - 31/12/2014

Abstract

The following open questions will be addressed in the project: How will the coherent properties of the pair condensate be modified in quantum-mechanically confined geometries? What about the robustness of the pair condensate against disorder in the presence of quantum confinement? How can quantum-size effects be influenced by phase fluctuations of the order parameter?

Researcher(s)

Research team(s)

Irreversibility and efficiency in small-scale systems. 01/01/2011 - 31/12/2014

Abstract

In contrast to the basic microscopic laws in physics, which are symmetric on time reversal, most macrocopic phenomena are characterized by irreversible behavior. Recently exact expressions for the entropy production and thermodynamical efficiency were proposed. Within this project we want to investigate how these results can be applied to small-scale systems like two-dimensional quantum dots, classical Coulomb clusters, photoelectric and electro-chemical devices. The main goal of this project is to propose experimental systems and to determine with computer simulations the conditions under which the effects of irreversibility and efficiency in small-scale systems can be observed experimentally.

Researcher(s)

Research team(s)

Exotic (sub)mesoscopic superconductors. 01/01/2011 - 31/12/2014

Abstract

The main goal of the present project is the theoretical description of nano- and meso-scale phenomena in exotic superconductors, with emphasis on multiband (MB) and noncentrosymmetric (NCS) superconductivity.

Researcher(s)

Research team(s)

Magnetism in nano-pore graphene 01/01/2011 - 31/12/2012

Abstract

With possible applications in carbon based electronics and spintronics, nano- pore graphene (NPG) has great potential. We will study NPG theoretically and computationally with the use of microscopic tight-binding Hamiltonians. Focus will be on effect of defects in the nano-pore lattice and distributions of pore sizes and shapes on the band structure and magnetism of this material. Numerical codes will be developed to run on graphical processing units (GPU). The acquisition of a high-end GPU will benefit other researchers in the Condensed Matter Theory group at UA by introducing them to GPU computing and providing the opportunity to run codes on the new machine.

Researcher(s)

Research team(s)

Electronic structure of patterned graphene. 01/10/2010 - 30/09/2014

Abstract

Many of the fascinating properties of graphene follow from its gapless linear spectrum. However, most electronic applications rely on the presence of a gap. In this project we investigate by ab initio calculations how different ways of patterning graphene can be used to realize a band gap in graphene. We focus on graphene patterned into graphene/graphane nanoribbons, graphene patterned by hydrogen adsorption and by defects, and hybrid graphene structures.

Researcher(s)

Research team(s)

Three-dimensional dynamics of coupled condensates in multiband and multilayered superconductors. 01/10/2010 - 30/09/2013

Abstract

The present project builds on the extensive experience and collaborations related to static and dynamic properties of superconductors accumulated in my first research mandate. However, very non-trivial extensions to my earlier numerical approaches must be developed for successful realization of this project.

Researcher(s)

Research team(s)

Spin-orbit and many-body interaction in semiconductor nanostructures. 01/09/2010 - 28/02/2012

Abstract

This project represents a formal research agreement between UA and on the other hand the Federal Public Service. UA provides the Federal Public Service research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

SILASOL - New Silicon Materials for Solar Applications. 01/01/2010 - 31/12/2013

Abstract

Silicon solar cells are the work horse of the photovoltaic energy conversion from sunlight into electricity.The SILASOL project focuses on new silicon-based materials for PV applications: by changing the shape of the silicon material (thinner wafers, nanowires, ...), or the synthesis method (CVD, mechanical cleavage, ...), the "new" Si material acquires specific properties (bandgap, crystallinity, ...) that can be used advantageously for PV applications. The technology development is in Imec (Leuven), the task of the UA is the experimental and computational characterization of these advanced silicon nanostructures.

Researcher(s)

Research team(s)

Metal-insulator transitions in electron correlated systems. 01/01/2010 - 31/12/2013

Abstract

In this project, the goal is to induce a metal-insulator transition (MIT) in an oxide thin film, above room temperature, using a low voltage. There exists a broad range of materials that display a MIT, typically as a function of temperature or as a function of doping. The most prominent candidates for this study are compounds with strong electron correlation such as the cuprates, the manganates and the vanadates.

Researcher(s)

Research team(s)

CONGRAN: Confinement in Graphene Nanostructures. 01/01/2010 - 31/12/2012

Abstract

The qualitative goal of the project is to demonstrate and exploit the novel scientific possibilities of tunable gdots in comparison to conventional quantum dots defined in semiconductor heterostructures. We will investigate spin effects in the energy spectrum of gdots, the modified spin blockade in gdot systems and the transport properties of gdots under Coulomb blockade at elevated temperatures.

Researcher(s)

Research team(s)

Study of composite superconducting nanowires. 01/10/2009 - 30/09/2012

Abstract

The present project proposes to numerically solve the quantum mechanical mean-field equations describing superconductivity at a microscopic level. We will refine a novel method in order to consider various inhomogeneous situations: presence of impurities, surfaces, interfaces and/or magnetic fields. We will then apply this method to problems of interest related to nanoscale superconductivity.

Researcher(s)

Research team(s)

Nanoscale phenomena in non-centrosymmetric superconductors. 01/07/2009 - 31/12/2013

Abstract

The non-conventional superconductors have been in the very focus of scientific research in the past 20 years. Within this group, a new class ¿ non-centrosymmetric superconductors (NCS) have been discovered in 2005 (e.g. CePt3Si, UIr, CeRhSi3). Those have crystal structure without inversion center(s), and within this project we study the exotic breaking of both spatial and time symmetry of essential superconducting phenomena in mesoscopic NCS samples.

Researcher(s)

Research team(s)

Monte Carlo simulations of molecular crystals 01/02/2009 - 31/12/2010

Abstract

The use of symmetry-adapted rotator functions in Monte Carlo simulations of molecular crystals is developed. The method is formulated in general and then applied to C60.C8H8 and C70.C8H8 fullerene cubane crystals. In addition, the role of the bilinear translation rotation coupling in C60.C8H8 and C70.C8H8 is investigated.

Researcher(s)

Research team(s)

Field-driven phenomena in three-dimensional magnetic elements. 01/02/2009 - 14/09/2009

Abstract

This project deals with truly 3D magnetic elements on the nanoscale, which are since recently realizable in experiment. We will study the 3D magnetization reversal in various polyhedra and core-shell structures where competing geometries and anisotropies may further enrich the novel phenomena. Understanding the physics involved will eventually lead to novel guiding principles for 3D magnetic data storage and improved magnetic logic devices.

Researcher(s)

Research team(s)

Nanostructured and nonhomogeneous quantum wires. 01/01/2009 - 31/12/2012

Abstract

The objective of this project is the theoretical study of the electronic properties of: - Lateral and radial nanostructured quantum wires. We will investigate the optical and transport properties. - Nonhomogeneous quantum wires. Study of effects due to geometrical fluctuations (i.e. lateral variations in the radius), of disorder, and of scattering on impurities and phonons on the electronic transport.

Researcher(s)

Research team(s)

Nanoengineering of layered superconducting systems for controlled THz radiation. 01/01/2009 - 31/12/2011

Abstract

Terahertz (THz) science and technology is highly applicable across all scientific areas. Despite of some realized THz sources, there is still a lack of a concept for a single-chip and controllable THz device. In this project we aim to analyze mechanisms for control of THz radiation in either artificial super-conducting/magnetic multilayers, or high-Tc and ferromagnetic superconductors, using the THz frequency range of Josephson plasma waves and their interaction with magnetic inclusions and applied magnetic field.

Researcher(s)

Research team(s)

Superconductor/ferromagnet hybrids, and spintronics in hybrid materials. 01/10/2008 - 30/09/2018

Abstract

Hybrid nanostructures consisting of a superconducting and a ferromagnetic metallic component, are one of the most interesting study objects, mainly because of their fascinating property to harbor two antitheses in the condensed matter physics - superconductivity and ferromagnetism. At the nanometer scale this combination leads to several important aspects for both fundamental and applied research. The goal is to form a suitable theoretical basis to study such hybrid composites, and further propose their exact realization - as a functional material, with desired electronic and magnetic properties. On the other hand, spintronics is currently a very challenging and rapidly evolving domain within the physics of condensed matter. There one aims to control both the spin and the charge carriers in electronic devices. Spintronic samples intriniscally combine the properties of magnetic and semi-conducting materials, and are therefore supposed to be fast, non-volatile and versatile, and capable of the simultaneous storage and processing of data at a low energy cost.

Researcher(s)

Research team(s)

Nanostructured semiconductor/magnet/superconductor hybrids. 01/10/2008 - 30/06/2013

Abstract

Novel nanoscale phenomena in nano-engineered artificial semiconductor-magnet-superconductor hybrids will be studied theoretically. Different bi- and multi- component hybrid structures will be investigated, in search of improved functionalities of envisaged superconducting and spintronics devices. The proposed collaboration involves the Condensed Matter Theory group (UA) and the Institute for Theoretical Sciences (University of Notre Dame, USA).

Researcher(s)

Research team(s)

(Self-)organization, dynamics and transport in finete systems. 01/10/2008 - 30/09/2011

Abstract

Objectives 1. Investigation of the effect of the finite size of the system. Study of crystallization, melting and glass formation. 2. Investigation of linear and non-linear dynamics of such systems under the influence of an external force. ¿ Linear: research of diffusion properties in a polydisperse system and the influence of the dimensionality of the system. ¿ Non-linear: Research of the influence of a fluid current on the colloidal particles or of another external force. The conditions for separation of between different particles in a polydisperse mixture will be investigated. The flow of particles in a monodisperse system in a pinning lattice will also be investigated.

Researcher(s)

Research team(s)

Ab initio calculations of semiconductor nanowires. 01/10/2008 - 30/09/2010

Abstract

In this project we will perform ab initio total-energy calculations within the pseudopotential density-functional theory (DFT) on experimentally realized nanoclusters and nanowires. This approach allows us to study, on an atomic scale, the structure and electronic properties of these semiconducting nanocrystals.

Researcher(s)

Research team(s)

Nanoengineering of layered superconducting systems for controlled THz radiation. 01/10/2008 - 30/09/2009

Abstract

Terahertz (THz) science and technology is highly applicable across all scientific areas. Despite of some realized THz sources, there is still a lack of a concept for a single-chip and controllable THz device. In this project we aim to analyze mechanisms for control of THz radiation in either artificial super-conducting/magnetic multilayers, or high-Tc and ferromagnetic superconductors, using the THz frequency range of Josephson plasma waves and their interaction with magnetic inclusions and applied magnetic field.

Researcher(s)

Research team(s)

Graphene: Modeling of transport. 01/02/2008 - 15/07/2012

Abstract

This project represents a formal research agreement between UA and on the other hand a private institution. UA provides the private institution research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Nonlineair Dynamics in Nanosystems: Flux Quanta in Nanostructured Superconductors, Colloids, Nanocluster. 01/01/2008 - 31/12/2012

Abstract

Nanotechnology will be the technology of the 21st century. The major industrialized countries are comprehensively intensifying their research in material sciences with a focus on nanotechnology. Quantum-mechanical principles in nano-structured materials respresent one of the most exciting fields of modern physics. Nano-structured superconductors (NSSC) play a special role due tot the macroscopic quantum state of the superconducting charge carriers and the appearance of quantized flux lines (vortices), which develop in the presence of a magnetic field. The proposed research is devoted to the in-depth study of the nonlineair dynamics of flux qaunta in NSSC and includes several related and interdisciplinary topics. Main targets are: -Implementation of new approaches to study the nonlineair dynamics of flux quanta in NSSC. Creation of new efficient ways to control the flux motion and critical parameters of NSSC. -Understanding of the nonlineair dynamics of antivortices in NSSC. Elaboration of a proposal for their dynamical experimental verification. -Understanding and calculation of the behavious of the critical temperature on the size and shape of superconducting nanograins. -Study of the nonlineair dynamicq and the principles of self-assembly of colloidal binary mixtures. -Understanding of the growth kinetics of nanoclusters, influence of the environment, surface formation, etc.

Researcher(s)

Research team(s)

Polydispersivity and anisotropy in static and driven quasi-one and two dimensional systems. 01/01/2008 - 31/12/2011

Abstract

To understand the controlling parameters that determine order in polydispersive infinite quasi-one and twodimensional strongly correlated systems consisting of classical constituents. Study of crystallization, glass formation and melting. Investigation of the transition from ID to 2D. Study of the linear and nonlinear dynamics of such systems when driven by an external force. Linear: normal modes (i.e. phonons) and the effect of dimensionality and inter-particle interaction (i.e. correlation) on diffusion. Non-linear: motion in the presence of obstacles or through constrictions. We will address issues such as pinning, depinning and jamming of the strongly correlated polydispersive system.

Researcher(s)

Research team(s)

Nanoscale superconductivity. 01/01/2008 - 31/12/2009

Abstract

The proposed research is aimed at investigating quantum-size effects in highly crystalline metallic superconducting nanowires and nanofilms. The project includes study of: (i) the thickness-dependent critical magnetic field (with and without spin effects); (ii) new Andreev-type states induced by quantum confinement in superconducting nanowires and nanofilms;(iii) the critical current in nanofilms and nanowires.

Researcher(s)

Research team(s)

Controlled terahertz radiation in layered superconducting systems 01/01/2008 - 31/12/2009

Abstract

Terahertz technology is highly applicable in all scientific areas. Despite of few realized THz sources, there is still a lack of a concept for a controllable THz device. In this project we aim to analyze mechanisms for control of THz radiation in either high-Tc and ferromagnetic superconductors or artificial hybrids, using the THz frequency range of Josephson plasma waves and their interaction with magnetic inclusions and applied magnetic field.

Researcher(s)

Research team(s)

Prize Research Council 2007. 19/12/2007 - 31/12/2007

Abstract

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Research team(s)

Nano-scale and low-dimensional correlated systems. 01/12/2007 - 31/12/2012

Abstract

Theoretical study of correlation effects in classical and quantum systems as e.g. low dimensional systems consisting of colloids, dusty plasma and nanostructures made of superconductors and graphene. Teams of complementary expertise in computational techniques and a common interest in multidisciplinary subjects are brought together.

Researcher(s)

Research team(s)

Static and dynamic vortex matter in nanostructured type-I and type-II superconductors. 01/10/2007 - 30/09/2010

Abstract

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Research team(s)

Controlling the Critical Parameters and Flux Motion in Nanostructured Superconductors. (CFNANOSC) 01/07/2007 - 30/06/2009

Abstract

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Research team(s)

Quantum effects in clusters and nanowires. 01/01/2007 - 31/12/2011

Abstract

This project represents a formal research agreement between UA and on the other hand the Federal Public Service. UA provides the Federal Public Service research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Structural and electronic properties of biologically modified graphene-based layers. 01/01/2007 - 31/12/2010

Abstract

Aims of the research project: (i) to optimize the preparation and patterning of graphene-based layers to which biomolecules are attachted and (ii) to understand the magnetotransport properties of such layers in a wide temperature range before and after attaching the biomolecules. The results of these investigations will be applied to develop a sensitive electronic monitoring of specific biological processes in a liquid environment, including the denaturation and rehybridization of DNA molecules, and the sensing of immunoglobulin and immunoglobulin-antigen binding.

Researcher(s)

Research team(s)

Controlling the Flux Motion in Nanostructured Superconductors. 01/01/2007 - 31/12/2008

Abstract

The proposed research is aimed at studying new superconducting (SC) materials and devices, operating in a wide range of magnetic fields and currents, through nano-structuring and effectively controlling the flux motion. It includes the study of: (i) controlled flux motion in nano-structured SCs with various arrays of pinning sites (APS): periodic, quasiperiodic, correlated random, and in nano-composite SCs; (ii) new vortex states including vortex clusters and giant vortices induced by pinning and confinement in SCs with APSs.

Researcher(s)

Research team(s)

Hybrid nanostructured superconductors. 01/01/2007 - 31/10/2007

Abstract

The vortex state in mesoscopic and nanostructured superconductors will be investigated when a superconductor is combined with a magnetic material. The approach will be based on a self-consistent solution of the Ginzburg-Landau equations through the method of simulated annealing.

Researcher(s)

Research team(s)

Structural and dynamical properties of fullerene hybrid systems: molecules in carbon nanotubes, cubane-fullerene mixed crystals, dynamics of a fullerene quantum gyroscope. 01/10/2006 - 30/09/2009

Abstract

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Research team(s)

Modelling of nanostructures and classical clusters. 01/10/2006 - 30/09/2008

Abstract

Researcher(s)

Research team(s)

Ab initio calculations of semiconductor nanocrystals: wires and clusters. 01/10/2006 - 30/09/2008

Abstract

In this project we will perform ab initio total-energy calculations within the pseudopotential density-functional theory (DFT) on experimentally realized nanoclusters and nanowires. This approach allows us to study, on an atomic scale, the structure and electronic properties of these semiconducting nanocrystals.

Researcher(s)

Research team(s)

FWO Visiting Postdoctoral Fellowship. (Pawel REDLINSKI, Poland) 01/10/2006 - 30/09/2007

Abstract

Study of the electronic properties of quantum wires using k.p-theory. Study of the exciton properties.

Researcher(s)

Research team(s)

Internal vibrational modes of fullerene molecules in C nanotubes. 01/03/2006 - 31/12/2007

Abstract

The interaction between C60 and other fullerene molecules encapsulated in carbon nanotubes is calculated. The relevance of the precise structure of the carbon nanotube is examined. The internal vibrational modes of the C60 molecules are investigated by numerical and analytical methods and compared to Raman scattering experiments. The orientation of fullerene molecules as a function of the diameter of the nanotube is studied.

Researcher(s)

Research team(s)

Critical and vortex phenomena in magnetically nano-structured superconductors. 01/03/2006 - 31/12/2007

Abstract

The aim of this project is to investigate a new class of phenomena, based on interaction between ferromagnets (FMs) and superconductors (SCs) when brought together within a nanometer scale. We will study vortex structures of SC/FM hybrids, such as thin SC-films with embedded magnetic nano-clusters, and submicron 3D SC/FM samples. Understanding the physics involved will lead to novel guiding principles for enhancing material and device functionalities.

Researcher(s)

Research team(s)

Nanoscale condensate and flux confinement in superconductors. 01/01/2006 - 31/12/2009

Abstract

Two main important new topics will be focussed upon : - nanoscale evolution of Tc and gap in individual 3D structures; - controlling vortex patterns and achieving vortex manipulation in superconductors and S/F hybrids with nanoscale pinning centers and magnetic field techniques.

Researcher(s)

Research team(s)

Strongly Coulomb coupled particle transport in plasmas and on solid substrates. 01/01/2006 - 31/12/2007

Abstract

This project belongs to the area of strongly correlated classical Coulomb systems. In the proposed project we will concentrate on: 1) strongly Coulomb correlations of dusty particles in a plasma environment, and 2) the deposition of such dusty particles on solid substrates.

Researcher(s)

Research team(s)

Calculations of strain in materials under stress using the finite element method. 01/01/2006 - 31/12/2007

Abstract

The calculation of stress and strain is not only important in engineering problems, but also in self-organised quantum dots. In this project, we wish to calculate the strain in self-organised quantum dots with complex geometries and compositions using the elasticity theory, as used by engineers. The calculations will be done using the finite element method which is the popular method for engineers. The results will be used as input for electronic structure calculations for self-organised quantum dots.

Researcher(s)

Research team(s)

Properties of dilute magnetic semiconductor quantum dots. 01/01/2006 - 31/12/2006

Abstract

The aim of the project is to study the interaction between electrons and magnetic ions, in particular Mn ions, in semiconductor quantum dots. A small number of Mn ions is placed in a quantum dot. The electronic properties will depend on the interaction with the magnetic ions, but also on the position of the ions in the system. A theoretical study on the magnetic and optical properties of such a new type of nanostructure will be performed.

Researcher(s)

Research team(s)

Prize Research Council 2005. 07/12/2005 - 31/08/2006

Abstract

Researcher(s)

Research team(s)

Ab initio calculations of semiconductor nanocrystals: wires and clusters. 01/10/2005 - 30/09/2006

Abstract

In this project we will perform ab initio total-energy calculations within the pseudopotential density-functional theory (DFT) on experimentally realized nanoclusters and nanowires. This approach allows us to study, on an atomic scale, the structure and electronic properties of these semiconducting nanocrystals.

Researcher(s)

Research team(s)

Theoretical study of two- and three-dimensional mesoscopic superconducting structures. 01/10/2005 - 31/08/2006

Abstract

The aim of the project is to give a theoretical description of the effects in mesoscopic superconducting structures of submicron dimensions.

Researcher(s)

Research team(s)

Ab initio calculations of semiconductor nanowires. 01/05/2005 - 30/04/2009

Abstract

Ab initio total energy calculations will be performed in the pseudopotential density functional theory formalism for the recently experimentally realised freestanding Si, Ge, ZnO, ... nanowires. This approach allows to study the atomistic and electronic structure of the nanowires. Also the influence of external molecules (like charge transfer) will be studied, to gain insight in the functioning of such wires as nanosensors.

Researcher(s)

Research team(s)

Ab initio calculations of semiconductor nanocrystals. 01/05/2005 - 31/12/2006

Abstract

Ab initio total energy calculations will be performed in the pseudopotential density functional theory formalism for the recently experimentally realised freestanding semiconductor nanowires and nanoclusters. This approach allows to study the atomistic and electronic structure of the nanowires and nanoclusters. Also the influence of external molecules (like charge transfer) will be studied, to gain insight in the functioning of such wires as nanosensors.

Researcher(s)

Research team(s)

Two- and three-dimensional mesoscopic superconductors. 01/05/2005 - 31/08/2006

Abstract

The aim of this project is to realize significant progress in the study of vortices in mesoscopic superconductors by coupling my theoretical calculations within the framework of the nonlinear Ginzburg-Landau theory with the new experimental results. The ongoing experimental progress is a unique opportunity for my research. In particular, we will concentrate on the study of giant vortex states and vortex shells in thin superconductors and three-dimensional vortices in realistic geometries.

Researcher(s)

Research team(s)

Theory and modeling for nano-technology. 01/04/2005 - 31/03/2009

Abstract

Theoretical study of the mesoscopic physics governing the electronic and electro-optical properties as well as the electronic transport characteristics of low-dimensional semiconductors or metallic structures that may act as the active areas of future nanodevices.

Researcher(s)

Research team(s)

Electronic properties of semiconductor quantum wires and quantum rings. 01/01/2005 - 31/12/2008

Abstract

The objective of this project is the theoretical study of the electronic properties of quantum wires and quantum rings.

Researcher(s)

Research team(s)

Computer modeling of nanosystems. 01/01/2005 - 31/12/2007

Abstract

Modeling of semiconductor nanowires and superconductor nanostructures. Optical and electrical properties of nanowires will be investigated for sensor applications. Ab initio calculations of the electronic structure of nano-systems. Three dimensional meso- and nano-superconductors will be investigated, respectively within the Ginzburg-Landau approach and the Richardson formalism.

Researcher(s)

Research team(s)

Spin polarization effects in diluted magnetic semiconductors (spin-DMS). 01/01/2005 - 31/12/2006

Abstract

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Research team(s)

Self-assembled semiconductor nanostructures for new devices in photonics and electronics. (SANDIE) 01/07/2004 - 30/06/2008

Abstract

This is a Network of Excellence dedicated to the formation of an integrated and cohesive approach to research and knowledge in the field of self-assembled semiconductor nanostructures. These nanostructures can then be cemented in position by the deposition of further layers of the substrate material. By varying the semiconductor materials involved, the growth conditions, and by vertically stacking layers of nanostructures, a rich variety of novel materials can be produced for the study of the fundamental properties of strongly confined systems, and for the development of advanced electronic and optoelectronic devices.

Researcher(s)

Research team(s)

Wigner Phase in Quantum Dots. 01/07/2004 - 30/06/2005

Abstract

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Research team(s)

Phase coherence in quantum dots. (FWO Vis.Fel., Alexei Vagov) 01/02/2004 - 31/12/2004

Abstract

Investigation of the mechanisms which are responsible for the loss of phase coherence in quantum dots. In order to be able to use quantum dots as qubits it is essential that the phase coherence is as large as possible and that one is able to diminish those mechanisms which contribute to phase decoherence.

Researcher(s)

Research team(s)

Hybrid systems on nanometerstructures. 01/01/2004 - 31/12/2008

Abstract

Research community between different flemish, wallons and non-Belgian laboratories. The following research subjects will be studied: study of metallic clusters; magnetic properties of nanostructures, spin dependent scattering; optical properties; study of two dimensional electron gas and quantum dots; theoretical modeling of nanostructures.

Researcher(s)

Research team(s)

Structure, phases and evolution far from equilibrium in classical systems with a finite numer of degrees of freedom. 01/01/2004 - 31/12/2007

Abstract

Three systems will be studied: 1) particles with atttractive forces, 2) particles with repulsive forces and confinement, and 3) negative mobility in Coulombsystems. Ginzburg-Landau densityfunctional theory and Monte Carlo simulations in combination with a gradient method will be used.

Researcher(s)

Research team(s)

Spin Polarization Effects in Semiconductors with Arrays of Magnetic Ions and Clusters. 01/01/2004 - 31/12/2007

Abstract

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Research team(s)

Electron correlations in nanostructures : classical and quantum systems. 01/10/2003 - 30/09/2006

Abstract

In this project we study the effects of electron correlations in quantum mechanical as well as classical systems. In the quantum mechanical part of this project, the current research in the electronic properties of quantum dots and coupled quantum dots will be continued and extended to multi-excitons and wires. In the classical part we study dynamical properties of classical clusters using molecular dyunamics simulation techniques.

Researcher(s)

Research team(s)

Vortex structures in mesoscopic superconductors. 01/10/2003 - 31/12/2005

Abstract

With the proposed project I want to achieve a collaboration with the experimental group of Prof. Kadowaki in Tsukuba (Japan) on determining the vortex positions in thin mesoscopic superconductors. Recently, this group has succeeded in visualizing the vortices. We, on the other hand, have the knowledge to determine theoretically the vortex positions. This collaboration would be an unique opportunity to couple our theoretical results to the experimental ones.

Researcher(s)

Research team(s)

Spin effects in nanostructured semiconductors. (Balazs MOLNAR, Hongarije) 01/07/2003 - 30/06/2004

Abstract

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Research team(s)

Canadian European Research Initiative On Nanostructures - 2. (CERION 2) 01/12/2002 - 31/05/2004

Abstract

This is the renewal of CERION. Its main purpose is the exchange of researchers and the organization of joint workshops. The University of Antwerp will collaborate with Prof. Vasilopoulos (Montreal) and Dr. Hawrylak (NRC, Ottawa).

Researcher(s)

Research team(s)

Theoretical study of mesoscopic superconducting structures. 01/10/2002 - 30/09/2005

Abstract

The aim of the project is to give a theoretical description of the effects in mesoscopic superconducting structures of submicron dimensions.

Researcher(s)

Research team(s)

Exciton-like complexes in real nanostructures. 01/10/2002 - 31/12/2004

Abstract

The behaviour of the exciton (bound state of a hole and an electron), its ions and its molecules in semiconductor nanostructures will be studied. In particular we will study the energy states and the optical properties of the exciton, and its molecules, in wire- and dot-shaped nanostructures. The nanostructures will be modeled to take into account deviation form the ideal model which are induced by the growth process. The effect of external magnetic and electric fields will be also taken into account.

Researcher(s)

Research team(s)

Theoretical research on charge correlation in low dimensional systems. 01/02/2002 - 31/01/2006

Abstract

Training in the physics of strongly correlated systems. Quantum as well as classical dots and molecules, colloids, dusty plasmas, ' are studied. Training in numerical techniques, finite difference methods, Monte Carlo and molecular dynamics simulations, density functional and Hartree-Fock theory.

Researcher(s)

Research team(s)

Structure and dynamics of vortices and charged particles in mesoscopic confined systems. 01/01/2002 - 31/12/2007

Abstract

Theoretical study of thermodynamic properties and time dependent phenomena in confined mesoscopic systems. Investigation of the driving forces behind ordering. The aim is to find the underlying principles governing order and melting in different two-dimensional experimental realizable systems.

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Spintronics. 17/12/2001 - 17/12/2004

Abstract

We will study the quantum mechanical principles underlying spintronics. Spin dependent tunneling, spin coherence and spin injection will be investigated.

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Correlations in Coulomb-interacting systems. 17/12/2001 - 17/12/2004

Abstract

In this project a number of topics will be studied. DFT will be extended towards the description of excited states and perfectly N-representable density matrices. In order to contribute to the understanding of optical properties of semiconductor systems, correlation effects on exitons and spin transport in heterostuctures will be studied. The influence of magnetic effects on clusters of 3d transition metal atoms will shed light on long-range coulomb behaviour. In an assessment of the performance of certain DFT functionals a number of calculations on molecules and clusters of interest to the farmaceutical industry as well as the nano-technology sector will be performed.

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Many-body effects in the dynamical properties of bilayer electron systems. 01/12/2001 - 30/11/2003

Abstract

This is a Marie Curie postdoctoral fellowship for Dr. Egidijus Anisimovas. Strongly interacting electrons in confined and extended bilayers will be studied where many-body effects are important and where a description beyond the mean field level is needed.

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Optical properties of nanostructured semiconductors. 01/10/2001 - 30/09/2005

Abstract

Study of Coulomb correlated electron-hole systems, i.e. exciton complexes. It will be investigated what is the influence of: the dimensionality of the superconducting system; the shape of the confinement; the interaction with the phonon modes of the semiconductor, and the influence of an external field.

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Self-assembled nanostructured materials for electronic and optoelectronic applications (NANOMAT). 01/10/2001 - 30/09/2004

Abstract

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Magneto-optical studies of exciton complex es and quantum mechanical coupling for improved quantum dot laser design. 01/08/2001 - 31/07/2005

Abstract

As primary components in fibre-optic telecommunication networks and optical data storage (CD), semiconductor lasers are an essential part of this information revolution. In this project we will study the magneto-optical properties of self-assembled quantum dots. Our goal is to support theoretically the experiments that exploit the effects of quantum mechanical coupling in order to improve their performance as lasers.

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Study of the properties of charge carriers in low dimensional structures. Quantum Hall effect, electron-phonon interaction, transport, polarons and superconductivity 01/10/2000 - 30/09/2009

Abstract

The aim of the project is a theoretical study of the properties of charge carriers in structures of reduced dimensionality consisting of semiconductors or the high temperature superconductors

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Surface electrons on mesoscopic structures. 01/10/2000 - 30/09/2004

Abstract

This is an EU-network which consists of a collaboration between 5 labs from the following countries: Belgium, England, France and Germany. The network is coordinated by F. Peeters. Experimental and theoretical research will be performed on novel mesoscopic structures from free electrons constrained to a structured surface of liquid helium. The interplay between electron correlation, confinement and the degree of quantum degeneracy will be studied.

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Mesoscopic and nanophysics of semiconductors and superconductors 01/01/2000 - 31/12/2003

Abstract

Theoretical study of the transport properties of mesoscopic systems and artificial nanostructures consisting of semiconductors and superconductors. Central in this study is that those systems consist of a finite number of degrees of freedom.

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Spin correlations and spin dependent transport in high magnetic fields. 01/01/1999 - 31/12/2003

Abstract

To obtain a deeper insight into the problem of spin correlations and the role of mobile charge carriers in transferring the spin orientations. This will be done by incorporating individual localized magnetic moments and/or their clusters in semiconductors or diluted magnetic semiconductors or semi-magnetic semiconductors. Study of spin dependent scattering of mobile charge carriers in "Giant" and "Colossal" magnetoresistance.

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Nanostructures: electronic, magnetic, and optical phenomena. 01/01/1999 - 31/12/2003

Abstract

Research community between different flemish, wallons and non-Belgian laboratories. The following research subjects will be studied: study of metallic clusters; magnetic properties of nanostructures, spin dependent scattering; optical properties; study of two dimensional electron gas and quantum dots; theoretical modeling of nanostructures.

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