Spin torque due to non-uniform Rashba spin orbit effect

TL;DR

This paper extends the understanding of spin torque effects caused by non-uniform Rashba spin-orbit interactions, proposing new torque terms and a device design that could significantly reduce switching currents in magnetic systems.

Contribution

It introduces three additional spin torque terms from non-uniform Rashba effects and proposes a device to lower switching currents.

Findings

Identified three new spin torque terms due to Rashba non-uniformity.

Proposed a Rashba gradient device for reduced switching currents.

Potential for orders of magnitude reduction in switching current.

Abstract

Following the early theoretical descriptions of the spin-orbit-induced spin torque [S.G. Tan et al., arXiv:0705.3502 (2007); S.G.Tan et al., Ann. Phys.326, 207 (2011)], the first experimental observation of such effect was reported by L. M. Miron et al., Nature Mater, 9, 230 (2010). We present in this article three additional spin torque terms that arise from the non-uniformity in magnetization space of the Rashba spin-orbit effect. We propose a simple Rashba gradient device which could potentially lower switching current by n orders of magnitude, where large n measures a small magnetization change.