Crystal fields and Kondo effect: new results for the magnetic susceptibility

TL;DR

This paper solves the thermodynamic Bethe ansatz equations for the Coqblin-Schrieffer model to analyze magnetic susceptibility with crystal fields at finite temperatures, revealing general features of Kondo systems.

Contribution

First analytic solution for pseudo-energies in the Coqblin-Schrieffer model with crystal fields, enabling detailed susceptibility calculations.

Findings

Susceptibility curves flatten at higher temperatures than specific heat.

Analytic expressions for pseudo-energies for N=4 states.

Applicability to dense Kondo systems and non-Fermi-liquid behavior.

Abstract

The thermodynamic Bethe ansatz equations for the Coqblin-Schrieffer model have been solved for the first time to obtain the magnetic susceptibility in the presence of crystal fields for non-zero temperatures. For the case of N = 4 effective ionic states an analytic expression for the limiting values of the pseudo-energies has been found facilitating the numerical solution for various crystal and magnetic field configurations. The single-impurity model applies to a wide range of dense Kondo systems and has been used before to explain apparent non-Fermi-liquid behavior. The flattening off of the susceptibility curves at a substantially higher temperature than the specific heat is shown to be a general feature of the Coqblin-Schrieffer thermodynamics.