Magnetic behavior of Dy3+ Ion in Dy2(SeO4)3 · 8H2O. Experimental and theoretical study including the effects of J-J mixing

Single crystals of dysprosium selenate octahydrate were grown and magnetic measurements carried out on the principal anisotropies and the principal susceptibility χ₁ at room temperature and their thermal variation down to 90 K. The magnetic moment is found to be slightly lower than the free-ion value, although the anisotropy is quite high. The variation of the average moment with temperature is very small and a least squares fit to a Curie-Weiss law yielded ?0.97 K as the paramagnetic Curie temperature. An analysis of the data was undertaken on the basis of interaction of the rare earth ion with its immediate neighbors. A crystal field (CF) of tetragonal symmetry which is the approximate site symmetry of the RE³⁺ ion, gave an excellent simulation of the observed behavior. Considerable effects of J-J mixing of the first three J-multiplets with the ground one were noticed. g-factors and the Schottky anomalies in the heat capacity were determined theoretically. Various hyperfine properties, including the thermal variation of the Mössbauer spectra, were computed for both isotopes of dysprosium in the light of the proposed CF.