Magnetostriction of Ytterbium and Cerium in YIG

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Abstract
Measurements using strain gauges of the magnetostriction constants of Yb3+ and Ce3+ ions in YIG are presented. The temperature dependence of the magnetostriction for Yb3+ in YIG is compared to theories by Callen and Callen based on crystal‐field (single‐ion) and anisotropic rare‐earth‐iron‐exchange (two‐ion) interactions. The measured temperature dependence of the magnetostriction for Yb3+ in YIG agrees closely with that predicted from the anisotropic exchange interaction. The measured temperature dependence of the magnetostriction of Ce3+ in YIG is difficult to interpret in terms of the two interactions because, in contrast to Yb3+, the sublattice magnetization cannot be evaluated analytically since the energy‐level scheme of the rare‐earth ground state is not completely determined and the higher levels of the ground state become populated at temperatures where the two interactions could be distinguished. The results are consistent with a ground‐state exchange splitting of Ce3+ in YIG of ∼200 cm−1. Recent paramagnetic‐resonance staticstrain measurements of Phillips and White are discussed.