Spin heat accumulation induced by tunneling from a ferromagnet

TL;DR

This paper demonstrates that spin heat accumulation caused by tunneling from a ferromagnet can generate measurable voltage signals and alter Hanle spin precession signatures, influenced by thermoelectric properties and heat resistance.

Contribution

It introduces the concept of spin heat accumulation induced by tunneling from a ferromagnet and analyzes its effects on voltage signals and spin precession signatures.

Findings

Spin heat accumulation produces measurable voltage signals.

The effect depends on the spin polarization of thermoelectric coefficients.

A spin-Wiedemann-Franz law relates spin heat and electrical spin resistance.

Abstract

An electric current from a ferromagnet into a non-magnetic material can induce a spin-dependent electron temperature. Here it is shown that this spin heat accumulation, when created by tunneling from a ferromagnet, produces a non-negligible voltage signal that is comparable to that due to the coexisting electrical spin accumulation and can give a different Hanle spin precession signature. The effect is governed by the spin polarization of the Peltier coefficient of the tunnel contact, its Seebeck coefficient, and the spin heat resistance of the non-magnetic material, which is related to the electrical spin resistance by a spin-Wiedemann-Franz law. Moreover, spin heat injection is subject to a heat conductivity mismatch that is overcome if the tunnel interface has a sufficiently large resistance.