We investigate the temperature dependent microwave absorption spectrum of an yttrium iron garnet sphere as a function of temperature (5 K to 300 K) and frequency (3 GHz to 43.5 GHz). At temperatures above 100 K, the magnetic resonance linewidth increases linearly with temperature and shows a Gilbert-like linear frequency dependence. At lower temperatures, the temperature dependence of the resonance linewidth at constant external magnetic fields exhibits a characteristic peak which coincides with a non-Gilbert-like frequency dependence. The complete temperature and frequency evolution of the linewidth can be modeled by the phenomenology of slowly relaxing rare-earth impurities and either the Kasuya-LeCraw mechanism or the scattering with optical magnons. Furthermore, we extract the temperature dependence of the saturation magnetization, the magnetic anisotropy and the g-factor.
@article{arxiv.1703.09444,
title = {Temperature dependent magnetic damping of yttrium iron garnet spheres},
author = {Hannes Maier-Flaig and Stefan Klingler and Carsten Dubs and Oleksii Surzhenko and Rudolf Gross and Mathias Weiler and Hans Huebl and Sebastian T. B. Goennenwein},
journal= {arXiv preprint arXiv:1703.09444},
year = {2017}
}