Non-adiabatic spin torque investigated using thermally activated magnetic domain wall dynamics

TL;DR

This study uses transmission electron microscopy to analyze thermally activated domain wall motion in permalloy nanowires, revealing how small currents influence the potential landscape and enabling measurement of non-adiabatic spin torque coefficients.

Contribution

It provides a novel experimental approach to quantify non-adiabatic spin torque using thermally activated domain wall dynamics in nanowires.

Findings

Non-adiabatic coefficient for transverse DW is 0.010 +/- 0.004.

Non-adiabatic coefficient for vortex DW is 0.073 +/- 0.026.

Thermal motion follows an Arrhenius law, modeling DW as a quasi-particle.

Abstract

Using transmission electron microscopy, we investigate the thermally activated motion of domain walls (DWs) between two positions in permalloy (Ni80Fe20) nanowires at room temperature. We show that this purely thermal motion is well described by an Arrhenius law, allowing for a description of the DW as a quasi-particle in a 1D potential landscape. By injecting small currents, the potential is modified, allowing for the determination of the non-adiabatic spin torque: the non-adiabatic coefficient is 0.010 +/- 0.004 for a transverse DW and 0.073 +/- 0.026 for a vortex DW. The larger value is attributed to the higher magnetization gradients present.