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Microscopic theory of spin-orbit torques applied to Skyrmion dynamics

Research paper by I. A. Ado, O. A. Tretiakov, M. Titov

Indexed on: 25 Mar '16Published on: 25 Mar '16Published in: Physics - Mesoscopic Systems and Quantum Hall Effect



Abstract

Spin-orbit torques of four different symmetries are related to a spin susceptibility tensor of linear response theory that is evaluated microscopically. The theory is applied to analyze Skyrmion dynamics induced by electric current in a ferromagnet/heavy-metal bilayer. We demonstrate that spin-orbit torques cannot affect azimuthally-symmetric Skyrmions with a topological charge larger than one. The motion of a Skyrmion with unit topological charge is shown to depend crucially on the type of disorder potential in the system. In particular, for spin-independent Gaussian disorder the effect of spin-orbit torque on the Skyrmion is negligible.