Nonlocal spin torques in Rashba quantum wires with steep magnetic textures

TL;DR

This paper develops a method to calculate nonlocal spin-transfer torques in Rashba quantum wires with steep magnetic textures, revealing complex spatial behaviors and effects on domain wall dynamics.

Contribution

It introduces a general procedure for calculating current-induced spin-transfer torques in systems with steep magnetic textures and Rashba spin-orbit interaction, highlighting nonlocal effects.

Findings

Spin-transfer torque is spatially non-local in steep magnetic textures.

Rashba spin-orbit interaction induces nonlocal field-like torque.

Steep textures exhibit markedly different domain wall dynamics.

Abstract

We provide a general procedure to calculate the current-induced spin-transfer torque which acts on a general steep magnetic texture due to the exchange interaction with an applied spin-polarized current. As an example, we consider a one-dimensional ferromagnetic quantum wire and also include a Rashba spin-orbit interaction. The spin-transfer torque becomes generally spatially non-local. Likewise, the Rashba spin-orbit interaction induces a spatially nonlocal field-like nonequilibrium spin-transfer torque. We also find a spatially varying nonadiabaticity parameter and markedly different domain wall dynamics for very steep textures as compared to wide domain walls.