Paramagnetic Behavior of Rare-Earth Ions in Some Orthoferrites

Abstract

Paramagnetic susceptibilities, χ_i(i=a,b,c) of single crystals of rare-earth orthoferrites RFeO₃ (R=Nd, Sm, Gd, Dy, Er, Yb and Y) were measured along the a, b and c axes at room temperature and 77 K. The main parts of the effective magnetic moments μ_eff,i’s were found to originate from rare-earth ions. All rare-earth ions except Dy³⁺ and Er³⁺ showed rather isotropic effective magnetic moments, which are nearly equal to those of the free ions. Er³⁺ and especially Dy³⁺ ions showed large anisotropy and the anisotropy increases with decreasing temperature. For Dy³⁺ μ_eff,b>μ_eff,a>μ_eff,c and for Er³⁺ μ_eff,c>μ_eff,a>μ_eff,b. The values of μ_eff,i for Dy³⁺ and Er³⁺ were obtained by using reported g-factors derived from optical experiments and the observed large anisotropy was found to result from the anisotropy of g-factor of the ground state.