Temperature-Dependent Lag in Polycrystalline Yttrium-Iron Garnet

Abstract

Certain samples of polycrystalline yttrium-iron garnet are characterized by a room-temperature permeability spectrum having two regions of dispersion, one at microwaves, the other at rf frequency. The former dispersion is identified as gyromagnetic in origin. The rf dispersion, which exhibits a temperature-activated shift to lower frequency with decreasing temperature, appears due to an electron-diffusion controlled domain-wall relaxation. The activation energy for the process is 0.38 ev.