Dynamics of Magnetic Skyrmions under Temperature Gradients

TL;DR

This paper investigates how magnetic skyrmions move under temperature gradients by extending the Zhang-Li spin-transfer torque model to finite temperatures, considering multiple thermal effects and addressing a recent controversy.

Contribution

It introduces a finite-temperature extension of the Zhang-Li model incorporating various thermal effects to clarify skyrmion motion direction under temperature gradients.

Findings

Skyrmions can move toward hot or cold regions depending on thermal effects.

Thermal dipole and entropy effects significantly influence skyrmion dynamics.

Theoretical results align with recent experimental observations.

Abstract

We expand the Zhang-Li spin-transfer torque [Phys. Rev. Lett. 93, 127204 (2004)] to finite temperatures by the scattering amplitude. Considering various factors including the adiabatic and diabatic effects of electrons and magnons, entropy equivalent field, thermal dipole field, thermal activation, magnetic-anisotropy gradient, and diffusion, we answer a recent question both experimentally and theoretically controversial: Will skyrmions move to the hot or cold region under thermal gradients?