# A Novel Spin-Orbit Torque due to Conduction Electrons

## TL;DR

This paper introduces a new spin-orbit torque mechanism caused by conduction electrons' scattering, which influences magnetization and has potential applications in optical magnetic switching.

## Contribution

It reveals a novel spin-orbit torque effect arising from conduction electron scattering, expanding understanding of current-induced magnetic phenomena.

## Key findings

- Identifies a new uniaxial anisotropy torque aligned with the current.
- Demonstrates the torque's relevance in high-current and laser pulse scenarios.
- Suggests practical applications in all-optical magnetic switching.

## Abstract

The anomalous Hall effect is mainly used to probe the magnetization orientation in ferromagnetic materials. A less explored aspect is the torque acting back on magnetization, an effect that can be important at high currents. The spin-orbit coupling of the conduction electrons causes spin-up and spin-down electrons to scatter to opposite sides when a charge current flows in the sample. This is equivalent to a spin current with orientation and flow perpendicular to the driving charge current, leading to a non-equilibrium spin accumulation that exerts a torque on the bulk magnetization through the s-d exchange interaction. The symmetry of this toque is that of an uniaxial anisotropy along the driving current. The large screening currents generated with laser pulses in all-optical magnetic switching experiments make for practical uses of this torque.