Spin torques and anomalous velocity in spin textures induced by fast electron injection from topological ferromagnets: The role of gauge fields

TL;DR

This paper introduces a novel analysis of magnetization dynamics caused by fast electron injection from topological ferromagnets, revealing how gauge fields induce spin torques and anomalous velocities affecting electrical conductivity.

Contribution

It proposes a new method to analyze spin textures under fast electron injection, highlighting the role of gauge fields in generating spin torques and anomalous velocities.

Findings

Injected electrons create a non-equilibrium magnetization density.

Gauge fields induce effective fields producing spin torques.

Anomalous velocity contributes to transverse electrical conductivity.

Abstract

A new method for analysing magnetization dynamics in spin textures under the influence of fast electron injection from topological ferromagnetic sources such as Dirac half metals has been proposed. These electrons, traveling at a velocity $v$ with a non-negligible value of $v/c$ (where c is the speed of light), generate a non-equilibrium magnetization density in the spin-texture region, which is related to an electric dipole moment via relativistic interactions. When this resulting dipole moment interacts with gauge fields in the spin-texture region, an effective field is created that produces spin torques. These torques, like spin-orbit torques that occur when electrons are injected from a heavy metal into a ferromagnet, can display both damping-like and anti-damping-like properties. Finally, we demonstrate that such an interaction between the dipole moment and the gauge field introduces an anomalous velocity that can contribute to transverse electrical conductivity in the spin texture in a way comparable to the topological Hall effect.