Growth-induced anisotropy of some mixed rare-earth iron garnets

Abstract

We have measured the growth-induced noncubic magnetic anisotropy under (110) facets of flux-grown garnet crystals at 300°K. The garnets studied have the general formula RM2Fe5O12, where R represents Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu, and M represents Y, Lu, or Gd. Measurements were made at room temperature in the (110) plane. The contribution of Gd and of all ions heavier than Tb is found to be small. The growth-induced anisotropy of all garnets containing Pr, Sm, Eu, or Tb is consistent with a model in which site preferences on the rare-earth sublattice are smooth functions of the ionic radius mismatch, and the single-ion magnetic anisotropy is due to anisotropic exchange. The anisotropy of the exchange appears to have the same sign and order of magnitude for all four ions. The behavior of Nd is anomalous and can be attributed to crystal field effects.