Electrical control of the Kondo effect in a helical edge liquid

TL;DR

This paper explores how electric-field-induced Rashba spin-orbit interaction can control the Kondo effect in quantum spin Hall insulators, revealing new ways to manipulate edge state conductance and uncovering conditions that obstruct Kondo screening.

Contribution

It demonstrates electric control over the Kondo effect in helical edge states and uncovers how anisotropic interactions can prevent Kondo screening, challenging previous assumptions.

Findings

Rashba interaction modulates Kondo temperature and conductance corrections.

Strong anisotropy can obstruct Kondo screening due to non-collinear spin interactions.

Electric control offers a new way to manipulate topological edge states.

Abstract

Magnetic impurities affect the transport properties of the helical edge states of quantum spin Hall insulators by causing single-electron backscattering. We study such a system in the presence of a Rashba spin-orbit interaction induced by an external electric field, showing that this can be used to control the Kondo temperature, as well as the correction to the conductance due to the impurity. Surprisingly, for a strongly anisotropic electron-impurity spin exchange, Kondo screening may get obstructed by the presence of a non-collinear spin interaction mediated by the Rashba coupling. This challenges the expectation that the Kondo effect is stable against time-reversal invariant perturbations.