Kondo resonance for orbitally degenerate systems

TL;DR

This paper investigates the Kondo resonance in a two-band Anderson model with orbital degeneracy using NRG calculations, revealing asymmetries and unique magnetic field effects on the resonance.

Contribution

It provides new insights into the asymmetric Abrikosov-Suhl resonance and the magnetic field response in orbitally degenerate systems, extending understanding beyond the standard Anderson model.

Findings

Asymmetric Abrikosov-Suhl resonance at quarter filling

Magnetic field causes asymmetric splitting and broadening

Kondo peak remains pinned against the Fermi level under magnetic field

Abstract

Formation of the Kondo state in general two-band Anderson model has been investigated within the numerical renormalization group (NRG) calculations. The Abrikosov-Suhl resonance is essentially asymmetric for the model with one electron per impurity (quarter filling case) in contrast with the one-band case. An external magnetic (pseudo-magnetic) field breaking spin (orbital) degeneracy leads to asymmetric splitting and essential broadening of the many-body resonance. Unlike the standard Anderson model, the ``spin up'' Kondo peak is pinned against the Fermi level, but not suppressed by magnetic field.