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.