Enhancement of the Kondo effect through Rashba spin-orbit interactions

TL;DR

This paper investigates how Rashba spin-orbit interactions influence the Kondo effect in a two-dimensional electron gas, revealing an exponential enhancement of the Kondo temperature and potential observable effects in various materials.

Contribution

It introduces a detailed analysis of the Kondo effect under Rashba spin-orbit interactions, highlighting the role of Dzyaloshinsky-Moriya terms and renormalization group effects.

Findings

Rashba interactions break spin SU(2) symmetry, leading to a two-band electron system.

The Dzyaloshinsky-Moriya term affects the Kondo coupling away from particle-hole symmetry.

Kondo temperature is exponentially enhanced due to the DM term's renormalization effects.

Abstract

We analyze the physics of a one-orbital Anderson impurity model in a two-dimensional electron gas in the presence of Rashba spin-orbit (RSO) interactions in the Kondo regime. The spin SU(2) symmetry breaking results in an effective two-band electron gas coupled to the impurity. The Kondo regime is obtained by a Schrieffer-Wolff transformation revealing the existence of a parity breaking term with the form of the Dzyaloshinsky-Moriya (DM) interaction. The DM term vanishes at the particle-hole symmetric point of the system, but it has important effects otherwise. Performing a renormalization group (RG) analysis we find that the model describes a two-channel Kondo system with ferro- and anti-ferromagnetic couplings. Furthermore, the DM term renormalizes the antiferromagnetic Kondo coupling producing an exponential enhancement of the Kondo temperature. We suggest that these effects can be observed in semiconducting systems, as well as in graphene and topological insulators.