On skyrmion stability

PIERRE PUJOL; S. A. OSORIO; H. D. ROSALES; D. C. CABRA; M. B. STURLA

San Carlos de Bariloche

Congreso; ICTP Workshop on Driven Quantum Systems; 2016

ICTP

A skyrmion is a nanoscale vortex-like spin structure that is stabilized by the Dzyaloshinskii-Moriya interaction (DMI) in a chiral lattice helimagnet [1]. Because of their topological stability, small size, high mobility and extremely low depinning current they are considered, within the field of spintronics, as promising information carriers in topological based logic and data storage devices [2]. Usually skyrmions are described as circular domain walls, i.e. as axisymmetric spin configurations. One important question is whether skyrmions are stable under shape deformations, that could be caused either by interactions within a given material or by external action. We propose a general description for asymmetric skyrmions, which provides a theoretical framework to systematically study their stability under arbitrary deformations. In this context, the anisotropic skyrmion is parametrized by means of two well-known variational Ans¨atze, namely the Belavin-Polyakov skyrmion and the Bogdanov approximation.Our approach can be used to study the large anisotropic deformations ofthe skyrmion internal structure recently observed in B20-FeGe thin layers under anisotropic strain [3].References[1] J. H. Han et al., Phys. Rev. B 82, 094429 (2010).[2] N. Nagaosa and Y. Tokura, Nature Nanotech., 8, 899-911 (2013).[3] K. Shibata, et al., Nature Nanotech., 10, 589-592 (2015).