Acoustic spin pumping: Direct generation of spin currents from sound waves in Pt/Y3Fe5O12 hybrid structures

TL;DR

This paper introduces acoustic spin pumping, a novel method where sound waves generated by a piezoelectric actuator induce spin currents in a Pt/YIG structure, which are then converted into measurable voltages via the inverse spin-Hall effect.

Contribution

The study demonstrates for the first time that sound waves can generate spin currents in a hybrid structure, providing a new approach to control spin dynamics using acoustic waves.

Findings

Successful detection of ISHE voltage induced by sound waves

Frequency-dependent measurements distinguish ASP signals from heating effects

Model calculations align with experimental observations

Abstract

Using a Pt/Y3Fe5O12 (YIG) hybrid structure attached to a piezoelectric actuator, we demonstrate the generation of spin currents from sound waves. This "acoustic spin pumping" (ASP) is caused by the sound wave generated by the piezoelectric actuator, which then modulates the distribution function of magnons in the YIG layer and results in a pure-spin-current injection into the Pt layer across the Pt/YIG interface. In the Pt layer, this injected spin current is converted into an electric voltage due to the inverse spin-Hall effect (ISHE). The ISHE voltage induced by the ASP is detected by measuring voltage in the Pt layer at the piezoelectric resonance frequency of the actuator coupled with the Pt/YIG system. The frequency-dependent measurements enable us to separate the ASP-induced signals from extrinsic heating effects. Our model calculation based on the linear response theory provides us with a qualitative and quantitative understanding of the ASP in the Pt/YIG system.