Elasto-Dynamical Induced Spin and Charge Pumping in Bulk Heavy Metals

TL;DR

This paper demonstrates that acoustic phonons can induce charge and spin currents in bulk heavy metals like platinum, with the spin current's magnitude depending on spin-orbit coupling and electronic relaxation time.

Contribution

The study introduces a first-principles Floquet approach to quantify elastodynamical-induced charge and spin pumping, revealing their dependence on relativistic effects and relaxation times.

Findings

Longitudinal charge pumping is intrinsic and nonrelativistic.

Transverse spin current depends on electronic relaxation time and is relativistic.

Both currents scale quadratically with elastic wave amplitude.

Abstract

Analogous to the Spin-Hall Effect (SHE), {\it ab initio} electronic structure calculations reveal that acoustic phonons can induce charge (spin) current flowing along (normal to) its propagation direction. Using Floquet approach we have calculated the elastodynamical-induced charge and spin pumping in bulk Pt and demonstrate that: (i) While the longitudinal charge pumping is an intrinsic observable, the transverse pumped spin-current has an extrinsic origin that depends strongly on the electronic relaxation time; (ii) The longitudinal charge current is of nonrelativstic origin, while the transverse spin current is a relativistic effect that to lowest order scales linearly with the spin-orbit coupling strength; (iii) both charge and spin pumped currents have parabolic dependence on the amplitude of the elastic wave.