Phenomenological spin transport theory driven by anomalous Nernst effect

TL;DR

This paper develops a phenomenological theory describing how the anomalous Nernst effect can drive spin transport in ferromagnetic multilayers, providing formulas for electric voltage and spin torque with implications for experimental detection.

Contribution

It introduces a new theoretical framework for spin transport driven by the anomalous Nernst effect in ferromagnetic multilayers, including derivations of electric voltage and spin torque formulas.

Findings

Electric voltage from spin current is about 0.1 μV with current parameters.

Temperature gradient needed for magnetization switching is larger than typical experimental values.

Discussion on separating Seebeck and transverse spin Seebeck effects contributions.

Abstract

Several experimental efforts such as material investigation and structure improvement have been made recently to find a large anomalous Nernst effect in ferromagnetic metals. Here, we develop a theory of spin transport driven by the anomalous Nernst effect in a diffusive ferromagnetic/nonmagnetic multilayer. Starting from a phenomenological formula of a spin-dependent electric current, the theoretical formulas of electric voltage and spin torque generated by the anomalous Nernst effect are derived. The magnitude of the electric voltage generated from the spin current via the inverse spin Hall effect is on the order of $0.1$ $\mu$V for currently available experimental parameter values. The temperature gradient necessary to switch the magnetization is quite larger than the typical experimental value. The separation of the contributions of the Seebeck and transverse spin Seebeck effects is also discussed.