MAGNETIC STUDIES ON ERBIUM BROMATE AND THE CRYSTAL-FIELD

Measurements of the principal magnetic susceptibilities of erbium brom ate single crystals in the temperature range 300-15.5 K have been made . The anisotropy at 300 K is high (\Delta X/X ($) over bar\ = 0.15) an d it increases very rapidly with decreasing temperature. The variation of X(perpendicular to) is nearly Curie-type down to the lowest temper ature attained, whereas the X(parallel to) versus T plot is nearly fla t. Smooth variation of X(perpendicular to) down to 15.5 K does not ind icate any structural phase transition of the crystal. The observed mag netic properties were analyzed for the first time invoking an effectiv e electrostatic interaction of the Er3+ i,, with its diamagnetic surro undings; the crystal field (CF) conforms to the approximate site symme try of Er3+, i.e. D-3b. The CF J-J mixing was included through term di agonalization 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 co mputed values of X(parallel to) in the range 60-500 mK reproduced the same sort of behavior as predicted by Simizu et al, in 1984. The therm al and hyperfine properties have been worked out.