Local Magnetic Field and Positive Muon Diffusion in Yttrium Iron Garnet

Abstract

We report positive muon spin rotation/relaxation (µ + SR) measurements on undoped yttrium iron garnet below 300 K in a ferrimagnetically ordered state. In zero field µ + SR measurements, static local magnetic fields were detected at 10 K in the range 0.7-1.2 T, which is consistent with the magnitude of the ordered magnetic moment. A gradual increase in a longitudinal muon spin relaxation rate was observed above 200 K with increasing temperature and attributed to thermally activated hopping of muons among magnetically inequivalent sites. The activation energy was estimated to be 0.170 (7) eV.