Electronic State and Magnetic Susceptibility in Orbitally Degenerate (J=5/2) Periodic Anderson Model

TL;DR

This paper investigates magnetic susceptibility components in a degenerate periodic Anderson model, revealing how orbital degeneracy influences susceptibility enhancement and Fermi liquid stability.

Contribution

It provides a detailed analysis of Pauli and Van-Vleck susceptibilities in an orbitally degenerate model, highlighting the role of degeneracy in susceptibility enhancement.

Findings

Both susceptibilities are enhanced by 1/z in the degenerate model.

Only Pauli susceptibility is enhanced in the nondegenerate case.

Orbital degeneracy reduces the Wilson ratio and stabilizes a nonmagnetic Fermi liquid.

Abstract

Magnetic susceptibility in a heavy fermion systemis composed of the Pauli term (\chi_P) and the Van-Vleck term (\chi_V). The latter comes from the interband excitation, where f-orbital degeneracy is essential. In this work, we study \chi_P and \chi_V in the orbitally degenerate (J=5/2) periodic Anderson model for both the metallic and insulating cases. The effect of the correlation between f-electrons is investigated using the self-consistent second-order perturbation theory. The main results are as follows. (i) Sixfold degenerate model: both \chi_P and \chi_V are enhanced by a factor of 1/z (z is the renormalization constant). (ii) Nondegenerate model: only \chi_P is enhanced by 1/z. Thus, orbital degeneracy is indispensable for enhancement of \chi_V. Moreover, orbital degeneracy reduces the Wilson ratio and stabilizes a nonmagnetic Fermi liquid state.