Model calculation of the frequency and temperature dependence of the electron-spin-resonance linewidth of aluminum

The linewidth of the electron-spin resonance in aluminum has been studied experimentally in many laboratories over the frequency range 1.3-80 GHz and at temperatures from 4 to 100 K. At low temperatures the width is thought to be due to motionally narrowed g anisotropy, and at high temperatures spin-flip scattering by phonons is assumed to dominate. Models are developed in this paper, based on previous calculations of the g anisotropy by Beuneu, which give a good semiquantitative account of the linewidth variation over the full range of frequency and temperature.