Intrinsic Coupling between Current and Domain Wall Motion in (Ga,Mn)As

TL;DR

This paper investigates the intrinsic coupling between current and domain wall motion in (Ga,Mn)As, highlighting the dominant role of spin-orbit interaction and scattering in determining damping and torque parameters, with implications for experimental detection.

Contribution

It introduces a theoretical framework expressing Onsager coefficients via scattering matrices, revealing intrinsic effects in (Ga,Mn)As that differ from extrinsic impurity scattering.

Findings

$eta_w$ is approximately 1, enabling detection of current or voltage induced by domain wall motion.

$eta_w$ is significantly larger than $ ext{α}_w$, indicating strong spin-orbit effects.

Intrinsic effects dominate over extrinsic impurity scattering in (Ga,Mn)As.

Abstract

We consider current-induced domain wall motion and, the reciprocal process, moving domain wall-induced current. The associated Onsager coefficients are expressed in terms of scattering matrices. Uncommonly, in (Ga,Mn)As, the effective Gilbert damping coefficient $\alpha_w$ and the effective out-of-plane spin transfer torque parameter $\beta_w$ are dominated by spin-orbit interaction in combination with scattering off the domain wall, and not scattering off extrinsic impurities. Numerical calculations give $\alpha_w \sim 0.01$ and $\beta_w \sim 1$ in dirty (Ga,Mn)As. The extraordinary large $\beta_w$ parameter allows experimental detection of current or voltage induced by domain wall motion in (Ga,Mn)As.