Topological damping Rashba spin orbit torque in ballistic magnetic domain walls

TL;DR

This paper reveals a topologically protected damping Rashba spin orbit torque in ballistic magnetic domain walls, challenging previous assumptions that torque components are topology-independent, and highlights its robustness and potential for spintronic applications.

Contribution

It demonstrates that the damping component of Rashba spin orbit torque depends on the topology of magnetic domain walls, introducing a new topological aspect to spin torque physics.

Findings

Damping Rashba spin orbit torque is topology-dependent in ballistic domain walls.

The torque component is robust against small deviations from ideal domain wall profiles.

This topological torque can influence current-driven domain wall motion in spintronic devices.

Abstract

Rashba spin orbit torque derived from the broken inversion symmetry at ferromagnet/heavy metal interfaces has potential application in spintronic devices. In conventional description of the precessional and damping components of the Rashba spin orbit torque in magnetization textures, the decomposition coefficients are assumed to be independent of the topology of the underlying structure. Contrary to this common wisdom, for Schr\"{o}dinger electrons trespassing ballistically across a magnetic domain wall, we found that the decomposition coefficient of the damping component is determined by the topology of the domain wall. The resultant damping Rashba spin orbit torque is protected by the topology of the underlying magnetic domain wall and robust against small deviations from the ideal domain wall profile. Our identification of a topological damping Rashba spin orbit torque component in magnetic domain walls will help to understand experiments on current driven domain wall motion in ferromagnet/heavy metal systems with broken inversion symmetry and to facilitate its utilization in innovative device designs.