Spin Nernst Effect of Antiferromagnetic Magnons in the Presence of Spin Diffusion

TL;DR

This paper develops a diffusive theory for the magnon spin Nernst effect in antiferromagnets, highlighting the importance of spin diffusion in converting bulk spin currents into detectable boundary signals, with implications for device design.

Contribution

It introduces a diffusive model incorporating boundary conditions to better understand spin Nernst effect detection in realistic antiferromagnetic devices.

Findings

Output signals increase with system size and saturate.

Optical detection is more effective than electronic detection.

Signals are even functions of magnetic field.

Abstract

Magnon spin Nernst effect was recently proposed as an intrinsic effect in antiferromagnets, where spin diffusion and boundary spin transmission have been ignored. However, diffusion processes are essential to convert a bulk spin current into boundary spin accumulation, which determines the spin injection rate into detectors through imperfect transmission. We formulate a diffusive theory to describe the detection of magnon spin Nernst effect with boundary conditions reflecting real device geometry. Thanks to the spin diffusion effect, the output signals in both electronic and optical detection grow rapidly with an increasing system size in the transverse dimension, which eventually saturate. Counterintuitively, the measurable signals are even functions of magnetic field, yielding optical detection more favorable than electronic detection.