Spin heat accumulation and its relaxation in spin valves

TL;DR

This paper investigates how spin-dependent electron temperatures in spin valves influence thermoelectric properties and violate classical laws due to inter-spin energy exchange mechanisms.

Contribution

It introduces the concept of spin heat accumulation and analyzes its effects on thermoelectric behavior in spin valves, considering both linear and far-from-equilibrium regimes.

Findings

Spin heat accumulation can lead to spin-dependent electron temperatures.

Inter-spin energy exchange affects thermoelectric properties.

Violations of the Wiedemann-Franz law are observed due to spin heat effects.

Abstract

We study the concept of spin heat accumulation in excited spin valves, more precisely the effective electron temperature that may become spin dependent, both in linear response and far from equilibrium. A temperature or voltage gradient create non-equilibrium energy distributions of the two spin ensembles in the normal metal spacer, which approach Fermi-Dirac functions through energy relaxation mediated by electron-electron and electron-phonon coupling. Both mechanisms also exchange energy between the spin subsystems. This inter-spin energy exchange may strongly affect thermoelectric properties spin valves, leading, e.g., to violations of the Wiedemann-Franz law.