Numerical Renormalization-Group Study of Particle-Hole Symmetry Breaking in Two-Channel Kondo Problem : Effect of Repulsion between Conduction Electrons and Potential Scattering

TL;DR

This study uses numerical renormalization-group methods to analyze how particle-hole symmetry breaking, due to electron repulsion and potential scattering, affects the non-Fermi liquid fixed point in the two-channel Kondo problem, revealing induced real spin overscreening.

Contribution

It demonstrates that realistic repulsion and potential scattering perturbations destabilize the non-Fermi liquid fixed point and induce overscreened real spin in the two-channel Kondo model.

Findings

Repulsion and potential scattering are relevant perturbations.

Induced real spin becomes overscreened and anomalous.

Conventional non-Fermi liquid fixed point is destabilized.

Abstract

Particle-hole symmetry breaking perturbation in two-channel pseudospin Kondo problem is studied by the numerical renormalization-group method. It is shown that the repulsion between conduction electrons at the impurity site and the single particle potential are the relevant perturbations against the conventional non-Fermi liquid fixed point. Although the repulsion (potential) with realistic strength prevents the overscreening of pseudospin, it induces in turn a {\it real spin}, which is also overscreened again. Thus the {\it real spin} susceptibility becomes anomalous contrary to the conventional two-channel Kondo problem.