Degenerate Anderson impurity model in the presence of spin-orbit and crystal-field splitting.

Abstract

Using a quantum Monte Carlo technique combined with the method of maximum entropy, we calculated the magnetic susceptibility and spectral properties of the degenerate single-impurity Anderson model in the presence of spin-orbit and crystal-field splitting. At small hybridization and moderate temperatures, the magnetic susceptibility displays a nonuniversal behavior. Under the influence of spin-orbit splitting, the magnetic susceptibility decreases due to the quenching of a sixfold-degenerate state to an effectively doubly degenerate state. The effect of crystal-field splitting on the magnetic susceptibility is less pronounced. The temperature dependence of the spectral function changes dramatically under the influence of spin-orbit splitting. In the accessible temperature regime, the central peak at \ensuremath{\omega}\ensuremath{\sim}0 decreases with decreasing temperature.