Kondo effect in the seven-orbital Anderson model hybridized with $\Gamma_8$ conduction electrons

TL;DR

This paper investigates the two-channel Kondo effect in a seven-orbital Anderson model with $b3$ conduction electrons, revealing residual entropy and constructing an effective model to understand quadrupole interactions.

Contribution

It provides a detailed numerical analysis of the two-channel Kondo effect in a complex orbital model and introduces an effective $j$-$j$ coupling scheme-based model for better understanding.

Findings

Residual entropy of 0.5 log 2 observed for the $b3$ doublet state

Effective $j$-$j$ coupling model reproduces two-channel $s$-$d$ physics

Recent results on three-electron case extend the analysis

Abstract

We clarify the two-channel Kondo effect in the seven-orbital Anderson model hybridized with $\Gamma_8$ conduction electrons by employing a numerical renormalization group method.From the numerical analysis for the case with two local $f$ electrons, corresponding to Pr$^{3+}$ or U$^{4+}$ ion, we confirm that a residual entropy of $0.5\log 2$, a characteristic of two-channel Kondo phenomena,appears for the local $\Gamma_3$ non-Kramers doublet state. For further understanding on the $\Gamma_3$ state, the effective model is constructed on the basis of a $j$-$j$ coupling scheme. Then, we rediscover the two-channel $s$-$d$ model concerning quadrupole degrees of freedom. Finally, we briefly introduce our recent result on the two-channel Kondo effect for the case with three local $f$ electrons.