Magnon-polaron control in a surface magnetoacoustic wave resonator

TL;DR

This paper demonstrates tunable hybrid magnon-phonon states called magnon-polarons in a YIG film coupled with a SAW resonator, achieving low dissipation and observing Rabi-like oscillations for the first time.

Contribution

It introduces a novel magnon-polaron cavity platform with tunable coupling and spatial confinement, enabling dynamic studies of hybrid spin-acoustic excitations.

Findings

Achieved magnon-polaron dissipation rates below 1.5 MHz.

Observed mode hybridization consistent with a phenomenological model.

First-time observation of Rabi-like oscillations in a SAW-spin wave system.

Abstract

Strong coupling between distinct quasiparticles in condensed matter systems gives rise to hybrid states with emergent properties. We demonstrate the hybridization of confined phonons and finite-wavelength magnons, forming a magnon-polaron cavity with tunable coupling strength and spatial confinement controlled by the applied magnetic field direction. Our platform consists of a low-loss, single-crystalline yttrium iron garnet (YIG) film coupled to a zinc oxide (ZnO)-based surface acoustic wave (SAW) resonator. This heterostructure enables exceptionally low magnon-polaron dissipation rates below $\kappa / 2\pi < 1.5\;$MHz. The observed mode hybridization is well described by a phenomenological model incorporating the spatial profiles of magnon and phonon modes. Furthermore, we report the first observation of Rabi-like oscillations in a coupled SAW-spin wave system, revealing the dynamical formation of magnon-polarons in the time domain. These results establish a platform for engineering hybrid spin-acoustic excitations in extended magnetic systems and enable time-resolved studies of magnon-polaron states.