Temperature Variation of FMR Linewidth in Metals

New measurements on FMR linewidths in high-purity single-crystal iron whiskers at 22 kMc/sec and 31 kMc/sec are reported at temperatures varying between 300° and 1000°K. It is shown that the observations can be accounted for by a relaxation parameter λ which is nearly independent of temperature. It is suggested that the low-temperature variation of the relaxation parameter in Ni and Fe may be qualitatively understood on the basis of spin-wave-conduction-electron interactions.