Two-channel Kondo Effect Emerging from Nd Ions

TL;DR

This paper demonstrates the emergence of the two-channel Kondo effect in Nd ions using a seven-orbital impurity Anderson model and numerical renormalization group analysis, revealing a residual entropy indicative of this phenomenon.

Contribution

It shows the realization of the magnetic two-channel Kondo effect in Nd$^{3+}$ ions through detailed modeling and numerical analysis, connecting to experimental candidates.

Findings

Residual entropy of 0.5 log 2 indicating two-channel Kondo effect

Identification of the effect in a wide parameter range for Nd ions

Connection to potential Nd compound observations

Abstract

We discuss Kondo phenomena in a seven-orbital impurity Anderson model hybridized with $\Gamma_8$ conduction electrons by employing a numerical renormalization group method. In particular, we focus on the case with three local $f$ electrons, corresponding to a Nd$^{3+}$ ion. For realistic values of Coulomb interactions, spin-orbit coupling, cubic crystalline electric field potentials, and hybridization, we find a residual entropy of $0.5\log 2$, a characteristic of two-channel Kondo phenomena, for the wide range of parameters of the local $\Gamma_6$ ground state. This is considered to be the magnetic two-channel Kondo effect, consistent with the result from an extended $s$-$d$ model constructed on the basis of the $j$-$j$ coupling scheme. Finally, we briefly discuss candidates of Nd compounds to observe the two-channel Kondo effect.