Anisotropy of the Magnetogyric Ratio of YIG

Ferromagnetic resonance measurements on a high‐quality single crystal sphere of yttrium iron garnet (YIG) have shown that this material cannot be described as having a scalar, isotropic magnetogyric ratio, and crystallographic anisotropy appropriate to cubic symmetry. Our present interpretation of the experimental observations is they can best be described by a model assuming tetragonal symmetry, though the distortion from cubic symmetry is certainly small. Using the simplest g tensor consistent with this symmetry, of the form g↔ =(gxxooogxxooogzz) we find that the g tensor components have the values gxx = 2.79483 ± .00003 MHz/oer, gzz = 2.79508 ± .00010 MHz/oer. Crystallographic anisotropy contributions up to the fourth power in the direction cosines of the magnetization have been included.