Multiferroic skyrmions - Maxim Mostovoy

Vendredi 20 octobre 2017 à 10 h 30

INSP - UPMC - 4 place Jussieu - 75005 Paris - Barre 22-23, 3e étage, salle 317

Maxim Mostovoy - Zernike Institute for Advanced Materials, University of Groningen, The Netherlands

Abstract

Skyrmions form an important class of topological defects in ordered states with a vector order parameter. Their non-trivial topology is a source of rich and interesting physics. Magnetic skyrmions have been recently observed in chiral magnets, such as the ferromagnetic metal, MnSi, and ferrimagnetic insulator, Cu₂OSeO₃. Berry phase acquired by electrons and magnons propagating through the non-coplanar skyrmion spin configuration gives rise to complex coupled dynamics of charges and spins mediated by effective gauge fields. Low critical currents needed to manipulate skyrmions opened a new active field of research – skyrmionics, which has a goal of developing skyrmion-based magnetic memory and data processing devices.

It was shown theoretically that isolated skyrmions, skyrmion crystals and other unusual multiply periodic states can exist in magnets with conventional centrosymmetric lattices where they are stabilized by competing exchange interactions [1-4]. Non-collinear magnetic orders in frustrated magnets spontaneously break inversion symmetry and induce an electric polarization. In my talk I will discuss stability and dynamics of skyrmions and half-skyrmions near the Lifshitz point as well as their ferroelectric properties which make possible to control these topological defects with an applied electric field.

 

[1] T. Okubo, S. Chung and H. Kawamura,  Phys. Rev. Lett. 108, 017206 (2012) .

[2] A. O. Leonov and M. Mostovoy, Nature Communications 6, 8275 (2015); 8, 14394 (2017).

[3] S. Hayami, S.-Z. Lin, and C. D. Batista, Phys. Rev. B 93, 184413 (2016).

[4] Y. A. Kharkov, O. P. Sushkov and M. Mostovoy, arXiv:1703.09173