Can the Spin-Orbit Interaction Break the Channel Degeneracy of the Two-Channel Orbital Kondo Problem?

TL;DR

This paper investigates whether spin-orbit interactions can break the channel degeneracy in the two-channel Kondo model involving two-level systems, finding that such effects are weak and only occur under specific symmetry-breaking conditions.

Contribution

It demonstrates that spin-orbit interactions can break channel degeneracy in the two-channel Kondo problem only with electron-hole symmetry breaking, but the effects are too weak to be observed.

Findings

Channel degeneracy breaking requires electron-hole symmetry breaking.

Spin-orbit interactions induce weak TLS-electron couplings.

Effects are relevant for heavy fermion systems.

Abstract

Two-level systems (TLS) interacting with conduction electrons are possibly described by the two-channel Kondo Hamiltonian. In this case the channel degeneracy is due to the real spin of the electrons. The possibility of breaking that degeneracy has interest on his own. In fact, we show that the interaction of the conduction electrons with a spin-orbit scatterer nearby the TLS leads to the breaking of the channel degeneracy only in the case of electron-hole symmetry breaking. The generated channel symmetry breaking TLS-electron couplings are, however, too weak to result in any observable effects. Our analysis is also relevant for heavy fermion systems.