Room temperature spin thermoelectrics in metallic films

TL;DR

This paper presents a theoretical study of spin thermoelectric effects in metallic films at room temperature, incorporating dynamical spin-orbit coupling with phonons and impurities, revealing new high-temperature relaxation mechanisms.

Contribution

It introduces the first theoretical model accounting for dynamical spin-orbit coupling effects in metallic films at room temperature, including novel relaxation processes.

Findings

Dynamical Elliott-Yafet spin relaxation and side-jump mechanisms are significant at high temperatures.

The interplay of intrinsic and extrinsic spin-orbit coupling causes nonlinear temperature dependence of conductivities.

The study focuses on transition metals like Pt, Au, and Ta relevant for experiments.

Abstract

Considering metallic films at room temperature, we present the first theoretical study of the spin Nernst and thermal Edelstein effects which takes into account dynamical spin-orbit coupling, i.e., direct spin-orbit coupling with the vibrating lattice (phonons) and impurities. This gives rise to two novel processes, namely a dynamical Elliott-Yafet spin relaxation and a dynamical side-jump mechanism. Both are the high-temperature counterparts of the well-known $T = 0$ Elliott-Yafet and side-jump, central to the current understanding of the spin Hall, spin Nernst and Edelstein effects at low $T$. We consider the experimentally relevant regime $T > T_D$, with $T_D$ the Debye temperature, as the latter is lower than room temperature in transition metals such as Pt, Au and Ta typically employed in spin injection/extraction experiments. We show that the interplay between intrinsic (Bychkov-Rashba type) and extrinsic (dynamical) spin-orbit coupling yields a nonlinear $T$- dependence of the spin Nernst and spin Hall conductivities.