Magnetic Susceptibility in a J=3/2 Kondo Model with a Tetragonal Crystal Field

A high-temperature signature of Kondo physics in heavy fermion materials can be the enhancement of Curie-Weiss temperatures, θ_CW∽T_K; however, it is unknown how potentially anisotropic Kondo couplings influence magnetic anisotropy. In addition, the analytical scaling behavior of Kondo couplings in realistic materials with crystal field splittings is not well understood. To address these problems, we study a J=3/2 Kondo impurity model with a tetragonal crystal field; perform a renormalization group procedure to obtain the scaling equations for the coupling constants; and examine the impact of scaling on the magnetic susceptibility at high temperatures. We find stable fixed points associated with a sole relevant doublet exhibiting an enhanced SU(2) Kondo effect and an SU(4) symmetric Kondo effect, among others. We discuss the behavior of the anisotropic susceptibility as certain fixed points are approached. Our analysis helps establish a correspondence between anisotropic Kondo couplings and experimentally observed anisotropic Curie-Weiss temperatures while developing a better understanding of experimentally relevant fixed points.