Hindering of hydrogen diffusion in stoichiometric yttrium iron garnet

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Abstract
Stoichiometric and nonstoichiometric yttrium iron garnet (YIG) films, both virgin and neon implanted, have been annealed in H2 atmosphere at temperatures up to 450 °C. The samples were measured by double-crystal x-ray diffraction, ferromagnetic resonance, and conversion electron Mössbauer spectroscopy. No evidence was found of reduction processes in the stoichiometric films. In particular, an evaluation of the upper limit δH for atomic hydrogen in the films after annealing gives δH∼10−2 afu. It is proposed that impurities have a central role in the problem of hydrogen diffusion. In particular Pb4+ → Pb2+ reduction may be a mechanism activating diffusion in nonstoichiometric YIG films.