Giant spin-vorticity coupling excited by shear-horizontal surface acoustic waves

TL;DR

This paper presents a theoretical and experimental study of spin-vorticity coupling induced by shear-horizontal surface acoustic waves, demonstrating significantly higher power absorption compared to Rayleigh waves and revealing strong coupling effects.

Contribution

It introduces a theoretical model for spin wave resonance generated by shear-horizontal surface acoustic waves via spin vorticity coupling, supported by experimental fabrication and measurements.

Findings

SH-SAW induces four orders of magnitude higher power absorption than Rayleigh SAW.

High-order frequency dependence of SWR observed in SH-SAW.

SVC strength comparable to magnetoelastic coupling.

Abstract

A non-magnetic layer can inject spin-polarized currents into an adjacent ferromagnetic layer via spin vorticity coupling (SVC), inducing spin wave resonance (SWR). In this work, we present the theoretical model of SWR generated by shear-horizontal surface acoustic wave (SH-SAW) via SVC, which contains distinct vorticities from well-studied Rayleigh SAW. Both Rayleigh- and SH-SAW delay lines have been designed and fabricated with a Ni81Fe19/Cu bilayer integrated on ST-cut quartz. Given the same wavelength, the measured power absorption of SH-SAW is four orders of magnitudes higher than that of the Rayleigh SAW. In addition, a high-order frequency dependence of the SWR is observed in the SH-SAW, indicating SVC can be strong enough to compare with magnetoelastic coupling.