Torque field and skyrmion movement by spin transfer torque in a quasi-2d interface in presence of strong spin-orbit interaction

TL;DR

This paper explores how spin transfer torque influences skyrmion movement at a ferromagnet interface with strong spin-orbit interaction, highlighting challenges and potential control methods in narrow nanowires.

Contribution

It introduces a quantum model for current and analyzes skyrmion dynamics considering both semiconductor and topological insulator interfaces with spin-orbit effects.

Findings

Skyrmion movement is hindered by spin-orbit interaction with in-plane currents.

Edge effects in nanowires can facilitate skyrmion control.

Differences between many-band and single-band torque fields are characterized.

Abstract

We investigate the torque field and skyrmion movement at an interface between a ferromagnet hosting a skyrmion and a material with strong spin-orbit interaction. We analyze both semiconductor materials and topological insulators using a Hamiltonian model that includes a linear term. The spin torque inducing current is considered to flow in the single band limit therefore a quantum model of current is used. Skyrmion movement due spin transfer torque proves to be more difficult in presence of spin orbit interaction in the case where only interface in-plane currents are present. However, edge effects in narrow nanowires can be used to drive the skyrmion movement and to exert a limited control on its movement direction. We also show the differences and similarities between torque fields due to electric current in the many and in the single band limits.