Spin accumulation in the spin Nernst effect

TL;DR

This paper investigates the spin Nernst effect, predicting observable spin accumulation driven by thermal gradients using Green's functions, and establishes a generalized Mott relation under specific symmetry conditions.

Contribution

It introduces a formalism that predicts spin accumulation without ambiguity and explores the effects in different models, including the Luttinger and Rashba models.

Findings

Predicts observable spin accumulation due to thermal gradients.

Derives a generalized Mott relation for spin and thermal responses.

Finds zero thermal spin accumulation in the 3D Luttinger model but nonzero in the 2D Rashba model.

Abstract

The spin Nernst effect is a phenomenon in which the spin current flows perpendicular to a temperature gradient. Similar to the spin Hall effect, this phenomenon also causes spin accumulation at the boundaries. Here, we study the spin response to the gradient of the temperature gradient with the use of Green's functions. Our formalism predicts physically observable spin accumulation without the ambiguity regarding the definition of the spin current or the magnetization correction. We prove the generalized Mott relation between the electric and thermal responses assuming the presence of time-reversal symmetry and the absence of inelastic scattering. We also find that thermal spin accumulation vanishes for the three-dimensional Luttinger model but is nonzero for the two-dimensional Rashba model with $\delta$-function nonmagnetic disorder in the first Born approximation.