Magnetic Susceptibility of the Orbitally Degenerate (J= 5/2) Periodic Anderson Model - Analysis on the Basis of the Fermi Liquid Theory

TL;DR

This paper resolves the longstanding question of how strong correlations affect the Van Vleck component of magnetic susceptibility in the orbitally degenerate Periodic Anderson Model, demonstrating significant enhancement via Fermi liquid theory.

Contribution

It provides a comprehensive analysis of the Van Vleck susceptibility in the strongly correlated regime using the $d= abla$ approximation and vertex corrections, revealing its enhancement.

Findings

Van Vleck term is highly enhanced in strong correlation regime

Wilson ratio is approximately 1 in metallic systems

Explains enhanced magnetic susceptibility in Kondo insulators

Abstract

In the orbitally degenerate ($J=5/2$) Periodic Anderson Model, the magnetic susceptibility is composed of both the Pauli term and the Van Vleck term, as is well known. The former is strongly enhanced by the strong correlation between $f$-electrons. But, for the latter, the influence of the strong correlation has been obscure for years. In this paper we give the solution of the longstanding problem. With the aid of the $d=\infty$ approximation, we study this problem on the basis of the Fermi liquid theory with degenerate orbitals, taking account of all the vertex corrections in a consistent way. As a result, we obtain the simple expression for the magnetic susceptibility, and show unambiguously that the Van Vleck term is also highly enhanced} in the strong correlation regime. This fact explains naturally the enhanced magnetic susceptibility observed in many insulating systems (i.e., Kondo insulator). Moreover, we show that the Wilson ratio takes a value around 1 in the metallic system, in good agreement with experiments.