Absence of spin-mixed states in ferrimagnet Yttrium iron garnet

Abstract

The spectroscopic g-factor of epitaxial thin film Yttrium Iron Garnet (YIG) has been studied using a combination of ferromagnetic resonance spectroscopy and x-ray magnetic circular dichroism. The values obtained by the two techniques are found, within experimental error, to be in agreement using Kittel's original derivation for the g-factor. For an insulating material with an entirely Fe3+ configuration, a spin mixing correction to Kittel's derivation of the spectroscopic g-factor, as recently shown by Shaw et al. [Phys. Rev. Lett. 127, 207201 (2021)] for metallic systems, is not required and demonstrates that the spin mixing parameter is small in YIG due to negligible spin–orbit coupling.

Elucidation of orbital moment, anisotropy, and magnetic damping in epitaxial Fe3O4 films

“…Whilst the authors note a large difference in the uncorrected ratio of the orbital to spin moment as measured by FMR and XMCD for Ni, the difference between the two techniques for the uncorrected moment ratio of Fe is much smaller, suggesting a reduced spin mixing parameter. As the spin-mixing parameter is a consequence of spin-orbit coupling, the effect will be also be minimized in materials containing d 5 ions [33]. We therefore expect that the correction to the g-factor due to second-order spin-mixing terms to be small for Fe3O4, and well within our experimental uncertainty.…”