Research Milorad Milosevic

Abstract

Ever since the discovery of high-temperature superconductivity in late 1980's, cuprate superconductors have attracted immense attention in the literature. One of such materials, Bi2Sr2CaCu2O8+δ (BSCCO) was shown to sustain its superconducting state down to its 2D limit of a single monolayer, which then can be used to design functional 2.5-dimensional heterostructures. For example, having d-wave pairing symmetry, a twisted bilayer of BSCCO monolayers displays topological superconductivity with broken time reversal symmetry for some particular values of the twist angle, which holds promise for the construction of novel superconducting devices for applications in advanced communication systems and quantum computing. Further way from the 2D limit, BSCCO heterostructures can be constructed to exhibit a superconducting diode effect up to a high critical temperature, enabling their use in other fundamental superconducting electronics. The overarching theme of this joint doctorate is to provide multiscale modeling of selected superconducting electronic devices, where latter described BSCCO systems under the influence of applied magnetic field and electrical current are the main selected example for the 6-month research stay of the student in Antwerp. Owing to the recently established collaboration in China and India, we gained access to the experimental data on 2.5D BSCCO systems that will benefit from numerically tailored properties in this project, geared towards the optimal design of selected electronic devices.

Researcher(s)

• Promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

DELIGHT aims at excellence of Europe in nanoscience and impact in research and development at the highest level. The project focuses on multifunctional nanomaterials based on colloidal particles, organic/inorganic perovskites, and organic and biomaterials. Design and fabrication of these materials for state-of-the-art applications requires a high level of interdisciplinarity with expertise from chemistry, physics, material science, engineering, nanofabrication and biology, combined with the most advanced spectroscopy tools. The scientific objectives of DELIGHT are to establish a platform of highly versatile functional nanomaterials, with the use of machine learning and artificial intelligence for material/device development and characterization. The focus is on multifunctional hybrids, heterostructures, and assemblies, and to fully exploit their potential for catalysis, energy, lighting, plasmonics, and theranostics. The research is organized in 3 work packages (WPs) that target nanomaterial development, functional composites and in-depth characterization, and device applications. Social and training objectives are the education of young researchers in Europe on the highest level, with emphasis on interdisciplinarity that is fundamental in modern nanoscience, the advancement of technological know-how that enables a sustainable and eco-friendly modern society, and promotion of gender equality in the scientific landscape at all levels. These goals are implemented in a WP dedicated to training, organizing lectures, workshops, technology transfer, and outreach and dissemination events. DELIGHT assembled an academic team of outstanding excellence, which links key players in the EU working on state-of-the-art nanomaterials with world leading universities in the US, Canada, and Argentina that are known for their unique scientific and technological capabilities and efficient technology transfer.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Covaci Lucian
• Co-promoter: Milosevic Milorad
• Co-promoter: Van Aert Sandra
• Co-promoter: Verbruggen Sammy

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Fabrication and design of metallic nanoparticles (NPs) has tremendously advanced over the last decades, enabling a variety of their applications. Many of the latter are based on heat delivery - utilizing plasmonic properties of such NPs, where exposure to light activates conducting electrons at the surface and heats the particle, with consequently transferred heat to the (biological, chemical, medical) environment the NP is embedded in. What is often disregarded is that NPs structurally change under such photo-thermal excitations. It is therefore of prime importance to understand the stability and behavior of metallic NPs at elevated and distributed temperature, and devise strategies for their optimized performance under desired conditions. That is the core objective of the present project, focusing on mono- and bimetallic Au and Ag NPs. To achieve this goal, it is first necessary to determine the atomistic structure of the NPs, for which one must go beyond the computationally expensive density-functional theory (DFT) calculations. For that, we will employ machine learning for training the Au and Ag interatomic potentials based on DFT data, towards incrementally sped up yet accurate relaxation of the NP shape and structure. The subsequent iterative coupling of the obtained morphology with spatially varying optical and thermal response is a cutting-edge development, that will enable us to predictively tailor the NPs under heating and light exposure, for any intended purpose.

Researcher(s)

• Promoter: Milosevic Milorad
• Co-promoter: Sevik Cem
• Fellow: Vlahovic Jovana

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

The supersolid, an intriguing counter-intuitive quantum state in which a rigid lattice of particles flows without resistance, has attracted long-time interest but has to date not been unambiguously realised. Alternative approaches have been proposed to Chester's original idea of a supersolid, where within the macroscopic quantum condensate the single particles are localized on each lattice site by strong repulsion. These include periodic density-modulated superfluids or clusters of condensates observed in cold atoms gases in optical lattices. Most recently, we have revealed a supersolid in double-layer heterostructures with interlayer excitons: electrons confined in a layer, coupled with holes, confined in a separated layer. This exciton supersolid is a Chester-type supersolid with one exciton per site and it shows over a wide range of layer separations, well within reach of the experimental capabilities but outside the focus of recent experiments. In this project, we aim to theoretically investigate how the existence and the stability of an interlayer exciton supersolid can be controlled and enhanced, by providing the phase diagram augmented by all supersolid phases. By controlling the layer separation (length of the exciton dipole) and the exciton density of the system, the exciton repulsions can be tuned to stabilize the supersolid with respect to the other excitonic phases and rich novel phenomena can be explored in the vicinity of the phase transitions.

Researcher(s)

• Promoter: Milosevic Milorad
• Co-promoter: Tempere Jacques
• Fellow: Conti Sara

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Modern Artificial Intelligence (AI) relies on artificial neural networks, which attempt to emulate the functionalities of the human brain through a set of highly interconnected nodes that play the role of artificial neurons, and may revolutionize the way we interact with technology. Currently, the most robust artificial neural networks are constructed using appropriate software models on CMOS hardware. However, how calculations are carried out on computers differs significantly from how the brain processes information. The prominent modern alternative are the wave-based physical systems. They have been recently demonstrated to operate as recurrent neural networks, where interference patterns in the propagating waves can realize an all-to-all interconnection between points of the host medium, exploiting the rich nonlinear dynamics that mimics the action of artificial neurons by scattering and recombining input waves in order to extract the carried information. Especially spin-waves (magnons) in magnetic films are promising candidates for practical applications due to their low power usage, strong nonlinearity arising from magnetization dynamics, and established scalability as well as integrability of magnetic nanostructures. Spin waves are readily employed for performing logic operations and recent advances have been made towards magnonic artificial intelligence, where different types of nanoengineered magnon scattering reservoirs have been explored. However, realizing the full potential of these ideas requires precise manipulation of spin waves in nanostructures, which is still a challenge and needs to be promptly advanced for the benefit of functional magnonic devices. In this project, we put forward magnonics in rapidly emerging 2D magnetic materials as a viable platform for neuromorphic and reservoir-computing applications. The magnetic properties of these atomically-thin, crystalline materials are extremely prone to electro-mechanical tuning, such as by lattice straining, gating, defect engineering, and/or layer stacking and heterostructuring. Furthermore, the recent observations of high-frequency (THz) spin-wave modes in monolayer CrI3 and room-temperature 2D ferromagnetism in several other materials put all the ingredients in place for the use of 2D magnetic materials as a technological platform for spin-wave-based neuromorphic computing. That said, theoretical and simulation insights are critically lacking in this field, which we aim to timely rectify in the present proposal. We will devise strategies to broadly and actively tune magnonic excitations and their propagation in selected 2D materials by nanoengineered structural and electronic stimuli, and engage to map out the viable realizations of neuromorphic computing in such materials, for which we will provide detailed theoretical recipes and in silico demonstrations. Considering that crystalline 2D materials offer a closest possible connection between the simulation environment and the practically measured quantities, our discoveries are bound to inspire experimental replication and further advances of magnonic technology.

Researcher(s)

• Promoter: Milosevic Milorad
• Co-promoter: Maciel de Menezes Rai
• Fellow: Oliveira da Silva Jean Felipe

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Topological insulators (the first-discovered and best known being Bi2Se3) have insulating bulk but conducting surfaces, and therefore exhibit uniquely exciting electronic properties. Their special surface states are protected by time-reversal symmetry and are hence robust against perturbations. Topological isulators have therefore attracted immense interest in condensed matter physics over the years, especially due to their versatile possible applications in quantum technology. However, due to strong spin-orbit coupling in these materials, applying any magnetization to them leads to novel (otherwise unattainable) quantum states, such as quantum anomalous Hall states, axion insulator states, and high Chern insulators, each of which are of high fundamental importance. Adding magnetization to topological insulators is typically achieved by doping with magnetic (ad)atoms, or constructing heterostructures with magnetic adlayers. In these so-called magnetic topological insulators, the time-reversal symmetry at surfaces may be broken by added magnetization, so unique topological states can appear, characterized by conductance quantized proportionally to the so-called Chern number. In recent years, the study of states with a Chern number higher than one has been at the forefront of research due to their potential application in multi-channel quantum computing and energy-efficient electronic devices (as their resistivity and associated Joule heating reduce proportionally to the Chern number). This PhD project provides a detailed theory of these emergent novel quantum states in magnetic topological insulators and their computational characterization in terms of stability and phase transitions as a function of size and direction of magnetization, applied magnetic field, sample thickness, strain, or gating. This research is based on initially built advanced (stationary and transport) real-space simulations of magnetic topological systems under external mechanical, electric and magnetic stimuli, using the tight-binding model, Landauer-Buttiker formalism, and material-specific ab initio data calculated in the host research group.

Researcher(s)

• Promoter: Milosevic Milorad
• Fellow: Shafiei Mohammad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Magnetic skyrmions, the nanoscale topologically swirling spin-textures, hold promise as information carriers for the next generation of low-power spintronic devices. On that path, enhancing their density, stability, and facilitating their creation, manipulation and detection are the key challenges. The recent discovery of intrinsic magnetism in two-dimensional (2D) van der Waals (vdW) materials has radically raised the expectations towards skyrmionic applications. The established ability to broadly tune properties of 2D materials by straining, gating, heterostructuring, makes them an ideal platform for controlling emergent magnetic phases, including skyrmionic ones. The latest experimental observation of ferromagnetic skyrmions in some vdW heterostructures strongly boosted the need for a skyrmionics roadmap in 2D materials that only theoretical simulations can provide, and that is the prime objective of this project. This goal requires developing an advanced multiscale methodology able to account for the manipulations by design in vdW systems, understanding the physics down to the very source of competing magnetic interactions, and detailing the magnetic phase diagrams of 2D materials as a function of mechanical, structural and electronic degrees of freedom, as well as the applied magnetic field and current. Our roadmap will also include the highly sought antiferromagnetic skyrmions, which will definitely promote skyrmionics in 2D materials to the technological paragon level.

Researcher(s)

• Promoter: Milosevic Milorad
• Fellow: Maciel de Menezes Rai

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

The realization of the first two-dimensional (2D) magnetic material in 2017 revolutionized the field and led to discovery of numerous other magnetic monolayers to date. Since these materials are all surface, they bear promise for facilitated planar transport of atomistic magnetic spin oscillations, called spin-waves or magnons. Coupled to the fact that properties of 2D materials are prone to extensive tuning by mechanical strain, electronic gating, or heterostructuring, magnetic monolayers offer a novel platform for magnonics by design that may outperform the electronics and spintronics of the modern day. On that path, the theoretical understanding and predictive modeling seem to lag behind the extremely fast experimental progress in the field. To change this unfavorable picture, this project will set up a multiscale methodology to provide a magnonic roadmap in mono- and bilayer spin-lattice systems of 2D magnetic materials. For that purpose, the modulations of microscopic magnetic exchange interaction in prominent mono- and bilayers will be detailed in presence of external stimuli and internal degrees of freedom, before reporting the resulting magnetic spin textures, and characterizing the propagation, velocity and frequency of magnonic excitations, with an outlook towards precisely controlled, long-range propagation of high-frequency magnons required for future technology.

Researcher(s)

• Promoter: Milosevic Milorad
• Fellow: Bacaksiz Cihan

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

DYNASTY's primary objective is to build in the European South East, and in particular in the Foundation for Research and Technology Hellas (FORTH) in Crete, a significant pole of attraction for nanomaterials researchers and scientists. This will be accomplished through joint research activities and partnering with two well-established European research teams, which are in the forefront of nanomaterials research. The activities will contribute in scientific production that will motivate and attract young scientists in nanomaterials (e.g. 2D materials) science and technology. The partners include: (a) the University of Antwerp (UA) with strong expertise in advanced Electron Microscopy for Materials Science and in Condensed Matter Theory (the EMAT and CMT groups, respectively), which are both part of the UA NANOlab Center of Excellence (Belgium) (b) and the National Institute of Applied Sciences (INSA- University of Toulouse), with deep expertise in advanced spectroscopic characterization techniques of 2D materials. The activities involve training through cross-lab visits, workshops, short courses, joint conferences, and well-designed communication activities to attract young scientists at FORTH. All teams will provide their expertise and collaborate to build advanced Imaging and Spectroscopy expertise at FORTH (combining non-linear and time-resolved optical spectroscopies) that will provide precise fine structural analysis of 2D materials and their heterostructures. By the end of the three-year project, FORTH will gain advanced skills in nanomaterials characterization and knowhow in nanoelectronic devices fabrication. As a result, DYNASTY will create a collaborative platform for widening experimental networks among nanomaterials labs in Europe, enabling local teams to produce excellent interdisciplinary nanoscience, currently lacking in Greece.

Researcher(s)

• Promoter: Verbeeck Johan
• Co-promoter: Bals Sara
• Co-promoter: Covaci Lucian
• Co-promoter: Milosevic Milorad

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

With conventional electronics almost reaching its physical limits, the search for beyond-silicon information technology has recently led to rapid advancements in magnonics - exploiting the use of magnetic spin-waves (magnons) to transmit, store and process information. Within the general quest for smaller and faster devices, current challenges in magnonics include scaling down to atomic limits and reaching switching speeds in the THz regime. In both respects, two-dimensional (2D) magnetic materials offer opportune research directions. The recent experimental observation of spin-waves with THz frequencies in atomically-thin magnetic materials, combined with their increased sensitivity to external stimuli compared to bulk counterparts, make 2D materials a nearly ideal platform for magnonics by design. Regarding the latter, moiré stacking of 2D materials (with moiré pattern stemming from lattice mismatch or twist between them) is the latest explored avenue for tailoring the emergent functionalities. Imprinting the moiré pattern of interactions into the materials' magnetic behavior is expected to lead to a plethora of novel magnonic features, such as the spatial control of magnonic propagation, formation of magnonic crystals and filters, and highly nontrivial magnonic dispersions – that can be further tuned by external magnetic field, gating, and strain – all being the subject of this fundamental exploratory project and all relevant to further development of magnonic circuitry.

Researcher(s)

• Promoter: Milosevic Milorad
• Fellow: Soenen Maarten

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Hydrogen is a renewable, high-energy-density and non-polluting energy carrier, hence its production and use are deservedly in prime attention of policy makers worldwide. In that respect, producing hydrogen using solar energy and photocatalytic water splitting presents both viable and environmentally friendly technology. However, progressing this technology to a widely applicable level requires an abundant yet highly efficient photocatalyst. Although many semiconducting materials have been proposed and synthesized for this purpose, some of them possess a relatively large bandgap with poor absorption for solar flux, while others suffer from the low photoexcited carrier rate, both of which severely decrease the photocatalytic performance. In addition, excitonic effects are usually neglected in the photocatalyst design, which leads to incorrect predictions of important properties such as optical absorption and band edge positions, ultimately yielding incorrect estimates of the key parameter - the solar-to-hydrogen (STH) efficiency. This project aims to radically change this unfavorable picture, and develop reliable predictive methodology to identify materials for photocatalytic water splitting with highest STH efficiency. The success of this project will not only advance the current modeling of photocatalysts, but will also provide cost-saving shortcuts to targeted experimentation towards viable technology for the use of water and light for hydrogen production.

Researcher(s)

• Promoter: Milosevic Milorad
• Co-promoter: Partoens Bart
• Co-promoter: Peeters Francois
• Fellow: Sun Minglei

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Junctions of superconducting materials lay the basis for the newest quantum technologies, especially quantum computing (pursued by Google, IBM, Intel,...), with capabilities far beyond classical approaches. However, the needed quantum coherence is severely limited by impurities and roughness at the interfaces in currently fabricated junctions. To resolve this, crystalline 2D materials are explored as alternative building blocks for superconducting junctions, because of their high purity and atomically sharp interfaces in their heterostructures. However, fundamental understanding of how the superconducting state is affected by joining different 2D materials is still lacking. Therefore, a new ab initio framework will be developed in this project, fully characterizing superconductivity in 2D heterostructures in presence of interlayer hybridization and competing quantum phases. This will yield insight into key properties like distribution and quantum tunneling of Cooper pairs across the junction, which lie at the heart of qubit applications. Motivated by the most recent experiments, both vertical and lateral junction architectures will be considered, and optimized through the available degrees of freedom, like twisting and stacking order, use of a buffer material in the junction, and tuning the junction through gating or strain. Such accumulated knowledge is indispensable to further advance and control qubit characteristics and quantum operations based on 2D superconductors.

Researcher(s)

• Promoter: Milosevic Milorad
• Fellow: Bekaert Jonas

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Novel materials that couple advanced magnetic and electronic properties are paramount to sustain the hunger of the modern society for advanced consumer electronics and Internet of Things, yet reduce the energy consumption and environmental impact. To satisfy the rather versatile needs of wearable, flexible, integrable, bio-compatible, ever smarter, and low power electronics, the paradigm shift is needed - towards tailored heterostructures, where different functionalities of the constituents are strongly coupled into a multifunctional hybrid. However, such strong interaction between different materials is challenging to realize, as much as their heterostructures are difficult to grow with sufficient control and quality. In this project, we will pursue the stacks of atomically-thin 2D materials as the most versatile yet fully controllable path towards shapeable magnetoelectronics by design. With properties broadly tunable by external mechanical, electric and magnetic stimuli, 2D materials are crystalline systems that nearly ideally connect the simulation environment to their practical behavior and measured quantities. To understand the deeply quantum phenomena behind the flexo-magnetoelectric coupling in 2D heterostructures, yet bridge them over to observables of practical value at micrometer scale, we formed a consortium of leading Belgian teams for suited multiscale simulations, the pioneer of 2D materials in UK for experimental validation, and imec as technology outlet.

Researcher(s)

• Promoter: Milosevic Milorad
• Co-promoter: Covaci Lucian
• Co-promoter: Partoens Bart
• Co-promoter: Peeters Francois

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Further technological advance of our modern society will critically depend on novel, all-in-one materials, able to couple magnetic, elastic, and electronic degrees of freedom in a controllable fashion. Atomically-thin 2D materials may be just what is needed, exhibiting a range of advanced properties, tunable by stretching, bending, gating, and/or heterostructuring. With advent of magnetism in 2D materials (only since 2017), tailoring their multifunctional behavior is at its prime potential. Magnetism in 2D materials is quite special, since any incurred symmetry change (with e.g. bending) affects magnetic interactions and causes adjacent magnetic moments to misalign, owing to strong emergent chirality, comparable to usual aligning interactions. Chiral interactions lead to observable nontrivial magnetic textures, such as skyrmions, and cause entirely different behavior of dynamic excitations (magnons), both of which bear documented technological promise. Symmetry breaking that causes chirality is also accompanied by local electric field, so that chiral magnetism and electric polarization in a 2D material are effectively coupled. This project is devoted to understanding of that coupling, and its response to standard manipulations within the realm of 2D materials, that will enable tailoring of chiral magneto-electronics practically at will, for actively and broadly tunable technology very sensitive to electric, magnetic, optical or mechanical stimuli.

Researcher(s)

• Promoter: Milosevic Milorad
• Fellow: Sabani Denis

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Nanomaterials play a key role in modern technology and society, because of their unique physical and chemical characteristics. The synthesis of nanomaterials is maturing but surprisingly little is known about the exact roles that different experimental parameters have in tuning their final properties. It is hereby of crucial importance to understand the connection between these properties and the (three-dimensional) structure or composition of nanomaterials. The proposed consortium will focus on the design and use of nanomaterials in fields as diverse as plasmonics, electrosensing, nanomagnetism and in applications such as art conservation, environment and sustainable energy. In all of these studies, the consortium will integrate (3D) quantitative transmission electron microscopy and X-ray spectroscopy with density functional calculations of the structural stability and optoelectronic properties as well as with accelerated molecular dynamics for chemical reactivity. The major challenge will be to link the different time and length scales of the complementary techniques in order to arrive at a complete understanding of the structure-functionality correlation. Through such knowledge, the design of nanostructures with desired functionalities and the incorporation of such structures in actual applications, such as e.g. highly selective sensing and air purification will become feasible. In addition, the techno-economic and environmental performance will be assessed to support the further development of those applications. Since the ultimate aim of this interdisciplinary consortium is to contribute to the societal impact of nanotechnology, the NanoLab will go beyond the study of simplified test materials and will focus on nanostructures for real-life, cost-effective and environmentally-friendly applications.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: De Wael Karolien
• Co-promoter: Janssens Koen
• Co-promoter: Lenaerts Silvia
• Co-promoter: Milosevic Milorad
• Co-promoter: Neyts Erik
• Co-promoter: Van Aert Sandra
• Co-promoter: Van Passel Steven
• Co-promoter: Verbruggen Sammy

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

In recent years layered graphene oxide (GO) membranes showed immense potential to overcome the limitations of conventional membrane materials with superior water flux and intriguing physical/chemical properties. However, its practical applications is still questionable mainly due to its undesirable swelling in water. To address this issue, meticulous understanding on the effect of the oxygen containing functional groups on the performance of layered GO membranes is of utmost importance, which is not available in the existing literature. Intercalation of cations could enhance aqueous stability of layered GO membranes. Inspired by this, I propose that also the generation of hydronium ions inside the interlayer gallery would impart aqueous stability of GO membranes. Hydronium ions could be generated by the dissociation of water molecules using an external electric field. Additionally, by constructing a membrane from a heterostructure of GO and reduced GO nanosheets, a balance between water flux and aqueous stability could be obtained. This could also lead to a Janus membrane with different wettabilities on the same membrane structure which could be effective in the separation of various oil-water mixtures. In this proposal, we will investigate all these aspects using atomistic simulations with extensive collaborations with different experimental and theoretical groups.

Researcher(s)

• Promoter: Neyts Erik
• Co-promoter: Milosevic Milorad
• Co-promoter: Peeters Francois
• Fellow: Gogoi Abhijit

Research team(s)

• Plasma Lab for Applications in Sustainability and Medicine - Antwerp (PLASMANT)

Project type(s)

• Research Project

Abstract

Stronger, lighter and more flexible than graphene, but with same planar structure, borophene holds promise revolutionize batteries, electronics, sensors, photovoltaics, spintronics, and quantum computing. Borophene is already proven as a catalyst used in hydrogen evolution, oxygen reduction, electrochemical reduction, possesses high hydrogen storage capacity due to the boron atom's low mass, and can be used for developing gas sensors. However, the use of borophene in functional materials is lagging behind, mainly because borophene oxidizes immediately upon exposure to air, making it nonconductive and ruining other potentially useful functional properties. On that front, it was recently shown that adatoms (such as hydrogen) stabilize borophene, and that its high reactivity can be impeded in bilayer or stacked borophene structures. In this project, we therefore exploren exactly the latter structures, i.e. doped mono- and bilayer borophenes, selectively functionalized or intercalated towards advanced electronic, magnetic, and superconducting properties, stable outside the vacuum chamber and not chemically active, making them applicable in emergent technology of the 21st century.

Researcher(s)

• Promoter: Milosevic Milorad
• Fellow: Soskic Bozidar

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Currently, one of the biggest challenges in the material science is the miniaturization of transistors and logic devices beyond the CMOS technology. One of the viable alternatives is to employ spintronics, particularly to use the topologically protected spin textures called skyrmions as carriers of bits of information. However, design of devices requires one's ability to precisely control the skyrmion motion and interactions. Therefore, in this PhD the controlled dynamics of skyrmions in a two-dimensional chiral magnet is explored, under influence of driving current and in presence of nanoengineered periodic arrays of pinning centers. The main goal is to map out different dynamic regimes and collective effects encountered during skyrmion motion, as a precursor for their custom-tailored use in information transfer and/or storage.

Researcher(s)

• Promoter: Milosevic Milorad
• Fellow: Vizarim Nicolas

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad
• Fellow: Sabani Denis

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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.

Researcher(s)

• Promoter: Milosevic Milorad
• Co-promoter: Peeters Francois
• Fellow: Pandey Tribhuwan

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad
• Fellow: Maciel de Menezes Rai

Research team(s)

• Condensed Matter Theory

Project website

Project type(s)

• Research Project

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

Researcher(s)

• Promoter: Milosevic Milorad
• Co-promoter: Bekaert Jonas
• Fellow: Petrov Mikhail

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad
• Co-promoter: Partoens Bart
• Fellow: Bekaert Jonas

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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.

Researcher(s)

• Promoter: Milosevic Milorad
• Co-promoter: Covaci Lucian
• Fellow: Zhang Lingfeng

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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.

Researcher(s)

• Promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad
• Co-promoter: Covaci Lucian
• Fellow: Zhang Lingfeng

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Both superconductors and fermionic superfluids are characterized by frictionless coherent flow, respectively of electron pairs and fermionic atom pairs. Usually, there is only one 'species' of electron pair in a superductor, and analogously only one type of atomic pair in a fermionic superfluid. Recently systems with mixtures of multiple species of pairs have caught the attention of researchers, as it became clear that the interplay of the different types of pairs leads to new behavior that was not expected on the basis of systems with only one type of pair. These systems are called 'multiband' superconductors or superfluids, and in this project we will set up the theoretical tools to model their behavior from the microscopic level up to the level of the macroscopic coherent behavior. With these tools we will systematically investigate how properties (such as critical field and temperature) and important flow patterns (such as vortex matter and solitons) are affected by the multiband nature of the system, and how this multiband nature can be engineered through quantum confinement. Moreover, we seek to characterize new quantum states emerging from the coupling between the different types of pairs.

Researcher(s)

• Promoter: Tempere Jacques
• Co-promoter: Milosevic Milorad

Research team(s)

• Theory of quantum systems and complex systems

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad
• Fellow: Roelants Sam

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Partoens Bart
• Co-promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad
• Co-promoter: Partoens Bart

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad
• Co-promoter: Peeters Francois
• Fellow: Roelants Sam

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad
• Fellow: Gillis San

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Objectives of the project: - Implementation of EGL theory in simulations. - Extension of EGL theory - Comparison of EGL theory to other phenomenological model.

Researcher(s)

• Promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad
• Co-promoter: Misko Vyacheslav

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad
• Co-promoter: Berdiyorov Golibjon

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

The main goal of this project is to understand the formation of metallic nanowires mediated by protein-derived biomolecular templates in such a way that the properties of the fabricated nanowires, including diameter and coverage, become controllable. This goal will be achieved by investigating the effect of different process parameters on the morphology of the nanowires. The structural information which is obtained by TEM and AFM will be combined with the outcome of the modeling studies.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Milosevic Milorad

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

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)

• Promoter: Peeters Francois
• Co-promoter: Milosevic Milorad
• Fellow: Covaci Lucian

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad
• Fellow: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project website

Project type(s)

• Research Project

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)

• Promoter: Peeters Francois
• Co-promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

The aim of the project is to develop efficient computational methods, based on Krylov space methods, to solve the linear and non-linear Schrödinger equations. This will enable the theoretical methods to move from the approximate 2D models to the more realistic 3D description. The methods will be applied to practical physical problems: to solve the non-linear time-dependent and time-independent Ginzburg-Landau equations for the study of the vortex structure and dynamics in mesoscopic superconductors and to solve the linear Schrödinger equation for realistic self-assembled quantum dots.

Researcher(s)

• Promoter: Vanroose Wim
• Co-promoter: Milosevic Milorad
• Co-promoter: Partoens Bart

Research team(s)

• Applied mathematics

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project

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)

• Promoter: Milosevic Milorad

Research team(s)

• Condensed Matter Theory

Project type(s)

• Research Project