Spin torque and force due to current for general spin textures

TL;DR

This paper calculates non-adiabatic spin transfer torque and forces in general spin textures using a quantum mechanical approach, revealing non-local effects and topological forces related to electric transport phenomena.

Contribution

It introduces a fully quantum mechanical calculation of non-adiabatic corrections to spin transfer torque for fast-varying spin textures, highlighting non-locality and topological origins.

Findings

Non-local spin torque due to fast-varying textures

Identification of a topological force in the adiabatic regime

Connection between forces and electric transport properties

Abstract

Non-adiabatic correction to spin transfer torque arising from fast-varying spin texture is calculated treating conduction electron fully quantum mechanically. The torque is non-local in space, and is shown to equivalent to a force (due to momentum transfer) acting on the center of mass of the texture. Another kind of force exists in the adiabatic regime, and is identified to be of topological origin. These forces are shown to be the counter reaction of electric transport properties, resistivity and Hall effect, respectively.