Analysis of high-field magnetization measurements on R2Fe14B single crystals (R=Tb, Dy, Ho, Er, and Tm)

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Abstract
Single crystals of the compounds R2Fe14B some 1–4 mm in size have been grown for a study of the anisotropy of the magnetization curves. These curves for crystals with R=Tb, Dy, Ho, Er, and Tm were measured at the Service National des Champs Intenses, Grenoble, between 4.2 and 275 K, with fields of 0–18 T being applied along the [100], [110], and [001] directions. Magnetization curves for all five compounds are analyzed in terms of the exchange and crystal field interactions (including terms up to sixth order, which may differ at 4 f and 4g sites) following the analysis previously developed for Nd2Fe14B. Molecular field coefficients representing the exchange interactions between R and Fe spins decrease from light to heavy R compounds as previously deduced from analysis of Curie temperatures. The CEF parameters are approximately the same across the series. In particular, the A20 terms are constant to within 10%.