Cavity optomagnonics with spin-orbit coupled photons

TL;DR

This paper demonstrates cavity optomagnonics using a ferromagnetic sphere supporting whispering gallery modes and magnons, revealing nonreciprocal scattering phenomena influenced by spin-orbit coupling and symmetry breaking, with potential applications in quantum optics and spintronics.

Contribution

First experimental realization of cavity optomagnonics with spin-orbit coupled photons showing nonreciprocal effects and angular-momentum selection rules.

Findings

Pronounced nonreciprocity in sideband signals

Observation of asymmetry in magnon-induced Brillouin scattering

Spin-orbit coupling influences scattering processes

Abstract

We experimentally implement a system of cavity optomagnonics, where a sphere of ferromagnetic material supports whispering gallery modes (WGMs) for photons and the magnetostatic mode for magnons. We observe pronounced nonreciprocity and asymmetry in the sideband signals generated by the magnon-induced Brillouin scattering of light. The spin-orbit coupled nature of the WGM photons, their geometric birefringence and the time-reversal symmetry breaking in the magnon dynamics impose the angular-momentum selection rules in the scattering process and account for the observed phenomena. The unique features of the system may find interesting applications at the crossroad between quantum optics and spintronics.