Fermi Surface and p-f Mixing Mechanism in CeSb

Abstract

Among the rare earth monopnictides which crystallize in the rocksalt type structure, Ce-monopnictides CeX (X=N,P,As,Sb and Bi) have a special position due to their anomalous properties. In particular, CeSb and CeBi have attracted much attention from both theoreticians and experimentalists due to their very unusual properties. They have very small crystal field splittings in the paramagnetic region (Birgeneau et al., 1973) but show very strong Ising type antisotropy (Bartholin et al., 1974, 1975) in the ordered states, which are separated by many phases (Rossat-Mignod et al., 1977; Fisher et al., 1978). To explain these anomalies, our theoretical group proposed the anisotropic p-f mixing model (Takegahara et al., 1980). In the paramagnetic region, according to the theory, the Г8 quartet states of 4f levels in the cubic field mix with the J=3/2 quartet states at Г point, while there is no mixing for the 4f Г7 doublet state. Therefore, the Г8 states are pushed down and cancel the splitting due to the point charge model in which Г7 is the lowest state.