Intrinsic Ferromagnetic Resonance Linewidth in Metal Single Crystals

The results of the measurements of the ferromagnetic resonance (FMR) linewidth in iron, fcc cobalt, nickel, silicon iron, and Permalloy single crystals at room temperature at 9.2 and 36.2 Gc/sec are given in the present paper. In these cases (except nickel) the linewidth can be fully explained by the exchange broadening due to skin effect and surface spin pinning. The assumed values of the surface anisotropy are not inconsistent with the values determined from spin-wave resonance of thin films. The hypothesis, that the intrinsic FMR linewidth of bulk metals (i.e., the linewidth measured in a both statically and dynamically homogeneously magnetized material) should be no more than several Oe (at least in some single crystals) is supported by the frequency dependence of FMR linewidth.