AC Voltage Generation by Spin Pumping and Inverse Spin Hall Effect

TL;DR

This paper investigates the generation of AC voltages via spin pumping and the inverse spin Hall effect in ferromagnet-normal metal systems, highlighting conditions for maximizing the effect and the importance of backflow in analysis.

Contribution

It provides a detailed computation of AC-ISHE voltages, demonstrating they can surpass DC signals and emphasizing the role of backflow in extracting accurate spin Hall parameters.

Findings

AC-ISHE voltages can be significantly larger than DC signals.

Optimal material combinations enhance AC-ISHE detection.

Including backflow is crucial for accurate parameter extraction.

Abstract

The polarization of the spin current pumped by a precessing ferromagnet into an adjacent normal metal has a constant component parallel to the precession axis and a rotating one normal to the magnetization. The former component is now routinely detected in the form of a DC voltage induced by the inverse spin Hall effect (ISHE). Here we compute AC-ISHE voltages much larger than the DC signals for various material combinations and discuss optimal conditions to observe the effect. Including the backflow of spins is essential for distilling parameters such as the spin Hall angle from ISHE-detected spin pumping experiments.