MAGNETIC-SUSCEPTIBILITY IN MAGNETIC POLARON SYSTEMS

An anomalous temperature dependence of magnetic susceptibility observed in the magnetic polaron systems such as CeP and CeAs is explained by an additional contribution from the magnetic polarons. The main contribution comes from the Gamma(8) state pulled down by the polaron. The motion of the polaron should be slow enough to guarantee the local thermal equilibrium. To explain strong temperature dependence, it is necessary to include the Gamma(8)-Gamma(8) interaction explicitly. Increasing number of polaron with decreasing temperature is particularly important to explain the result under pressure. Splitting of the Gamma(7) doublet in each magnetic polaron is also important at low temperature.