Spin-orbit-induced dynamics of magnetic textures

Abstract

We investigate the effect of the relativistic spin-orbit interaction on the dynamics of both ferromagnetic and antiferromagnetic domain walls driven by spin waves. Initially, we derive the free energy and the equations of motion of the order parameters in both systems. Subsequently, we introduce the relativistic spin-orbit interaction in the form of the Dzyaloshinskii-Moriya interaction.

To study the dynamics of domain wall, we proceed both analytically and numerically. We semi-classical one-dimensional continuum models valid in the classical spin limit, to describe the dynamics of the order parameters in both ferromagnets and antiferromagnets. This allows the use of the framework of classical field theory to obtain conservation laws governing the interaction between spin waves and domain walls.

First, we study systems with magnetic easy-axis anisotropy which allow for analytical calculations. Later, we introduce additional hard- axis anisotropy which we study mostly through numerical simulations. For ferromagnetic systems, we reproduce with good accuracy the earlier published results.

For antiferromagnetic system, we generalize an existing theory of propulsion of antiferromagnetic domain wall by circularly polarized spin wave to include the Dzyaloshinskii-Moriya interaction. Moreover, we demonstrate by numerical simulation the spin wave helicity dependence of the direction of spin wave induced domain wall motion in the presence of additional hard-axis anisotropy.

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