Magnetic studies on erbium bromate and the crystal field

Abstract

Measurements of the principal magnetic susceptibilities of erbium bromate single crystals in the temperature range 300-15.5 K have been made. The anisotropy at 300 K is high (|Δ X/ X | = 0.15) and it increases very rapidly with decreasing temperature. The variation of X ⊥ is nearly Curie-type down to the lowest temperature attained, whereas the X | versus T plot is nearly flat. Smooth variation of X ⊥ down to 15.5 K does not indicate any structural phase transition of the crystal. The observed magnetic properties were analyzed for the first time invoking an effective electrostatic interaction of the Er 3+ ion with its diamagnetic surroundings; the crystal field (CF) conforms to the approximate site symmetry of Er 3+, i.e. D 3h. The CF J-J mixing was included through term diagonalization and intermediate coupling effects were partly taken care of using appropriate reduced matrix elements. The computed values are in very good agreement with the corresponding observed values. Our computed values of X | in the range 60–500 mK reproduced the same sort of behavior as predicted by Simizu et al. in 1984. The thermal and hyperfine properties have been worked out.