Magnon polarons in the spin Peltier effect

Abstract

We report the observation of anomalous peak structures induced by hybridized magnon-phonon excitation (magnon polarons) in the magnetic field dependence of the spin Peltier effect (SPE) in a ${\mathrm{Lu}}_{2}{\mathrm{Bi}}_{1}{\mathrm{Fe}}_{4}{\mathrm{Ga}}_{1}{\mathrm{O}}_{12}$ (BiGa:LuIG) with Pt contact. The SPE peaks coincide with magnetic fields tuned to the threshold of magnon-polaron formation, consistent with the previous observation in the spin Seebeck effect. The enhancement of SPE is attributed to the lifetime increase in spin current caused by magnon-phonon hybridization in BiGa:LuIG.