Skyrmions in Chiral Magnets, Liquid Crystals, and Beyond

Date: 1 October 2019

Venue: Campus Groenenborger, Building U, Room 244 - Groenenborgerlaan 171 - 2020 Antwepren (route: UAntwerpen, Campus Groenenborger)

Time: 4:00 PM - 5:00 PM

Organization / co-organization: Condensed Matter Theory

Short description: Physics Department Seminar presented by Prof Charles Reichhardt from the Theoretical Division, Los Alamos National Laboratory, US



Skyrmions in Chiral Magnets, Liquid Crystals, and Beyond

Abstract

Skyrmions are topologically stable particle like objects initially proposed by Tony Skyrme in 1961 to explain aspects of particle physics such as Baryons and Mesons. Skyrmions have now been discovered in a growing number of systems including chiral magnets [1], liquid crystals [2], nonlinear optics [3], and Bose-Einstein condensates [4].  They are an outstanding example of an emergent phenomenon where the underlying microscopic degrees of freedom such as individual spins in the case of a chiral magnet can have relatively small changes from one spin to another; however, the ensemble of spins acting together form a larger scale object that behaves like an emergent particle or soliton.  Skyrmions in chiral magnets were discovered in 2009 and now have been found in a wealth of different kinds of materials including some in which skyrmions are stable at room temperature. These systems have attracted intense interest not only for their unique static and dynamic phases but also for their potential use in applications as information carriers in magnetic memory or logic devices [5]. Here we outline various aspects of skyrmions, particularly those in magnetic systems, the different types of phases they can exhibit, such as skyrmion crystals, glasses, or liquids, and the skyrmion dynamics, as well as the recent observation of related topological textures such as merons, polar skyrmions, antiskymions, and bound or quarklike confined skyrmions [6,7].

[1] S. Mühlbauer et al., Skyrmion lattice in a chiral magnet. Science 323, 915–919 (2009).
[2] A. Nych et al., Spontaneous formation and dynamics of half-skyrmions in a chiral liquid-crystal film. Nature Phys. 13, 1215 (2017).
[3] S. Tsesses et al., Optical skyrmion lattice in evanescent electromagnetic fields, Science 361, 993 (2018).
[4] W. Lee et al., Synthetic electromagnetic knot in a three-dimensional skyrmion.  Sci. Adv. 4, eaao3820 (2018).
[5] A. Fert et al., Magnetic skyrmions: advances in physics and potential applications.  Nature Rev. Mater. 2, 17031 (2017).
[6] S. Das et al., Observation of room-temperature polar skyrmions. Nature 568, 368 (2019).
[7] D. Foster et al., Two-dimensional skyrmion bags in liquid crystals and ferromagnets.  Nature Physics (2019).



Contact email: lucian.covaci@uantwerpen.be

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