Theory of electric reactance emerging from spin Hall effect

TL;DR

This paper provides a theoretical framework for understanding how the spin Hall effect induces an electric reactance in spintronic systems, revealing its frequency-dependent behavior and dependence on interfacial spin transfer mechanisms.

Contribution

It introduces a comprehensive theoretical model describing the emergent reactance due to the spin Hall effect, highlighting its inductor-like nature and sign dependence on spin transfer components.

Findings

Reactance becomes inductor-like below ferromagnetic resonance frequency.

Sign of reactance is governed by the spin transfer mechanism at the interface.

Reactance behavior can distinguish interfacial spin transfer processes.

Abstract

The spin Hall effect in a heavy metal intercorrelates an AC electric current to the magnetization dynamics in an adjacent ferromagnet, which manifests as an electric reactance in the system's current-voltage response. We present a comprehensive theoretical analysis for this emergent reactance contribution in the frequency regime relevant to transport measurements up to a few GHz. Our analysis reveals that the reactance becomes inductor-like at low frequency below the ferromagnetic resonance. Crucially, we find that the sign of the reactance is directly governed by the spin transfer mechanism at the interface, which depends on the competition between its damping-like and field-like components parametrized by the spin mixing conductance. This characteristic behavior in the reactance offers a powerful transport observable in distinguishing the interfacial spin transfer processes in spintronic materials.