Extrinsic spin Nernst effect in two-dimensional electron systems

TL;DR

This paper investigates the extrinsic spin Nernst effect in a symmetric 2D electron system with spin-orbit interaction, revealing how impurity potential types influence the sign of the spin-Nernst coefficient.

Contribution

It provides a theoretical analysis of the extrinsic spin Nernst effect considering skew scattering and side jump mechanisms in a symmetric quantum well.

Findings

Sign change of spin-Nernst coefficient at specific impurity densities for repulsive potentials

Contrast with spin Hall effect where sign change occurs for attractive potentials

Dependence of spin current direction on impurity scattering mechanisms

Abstract

The spin accumulation due to the spin current induced by the perpendicular temperature gradient (the spin Nernst effect) is studied in a two-dimensional electron system (2DES) with spin-orbit interaction by employing the Boltzmann equation. The considered 2DES is confined within a symmetric quantum well with delta doping at the center of the well. A symmetry consideration leads to the spin-orbit interaction which is diagonal in the spin component perpendicular to the 2DES. As origins of the spin current, the skew scattering and the side jump are considered at each impurity on the center plane of the well. It is shown that, for repulsive impurity potentials, the spin-Nernst coefficient changes its sign at the impurity density where contributions from the skew scattering and the side jump cancel each other out. This is in contrast to the spin Hall effect in which the sign change of the coefficient occurs for attractive impurity potentials.