Kondo screening suppression by spin-orbit interaction in quantum dots

TL;DR

This paper investigates how spin-orbit interactions and Aharonov-Bohm effects suppress the Kondo state in quantum dots, and demonstrates that an in-plane Zeeman field can restore the Kondo resonance and enable spin filtering.

Contribution

It reveals the suppression mechanism of the Kondo state due to spin-orbit interactions and proposes a method to restore the Kondo resonance using an in-plane Zeeman field.

Findings

Spin-orbit interactions suppress the Kondo singlet in quantum dots.

An in-plane Zeeman field can fully restore the Kondo resonance.

Restoration of the Kondo effect enables spin filtering and polarization.

Abstract

We study the transport properties of a quantum dot embedded in an Aharonov-Bohm ring in the presence of spin-orbit interactions. Using a numerical renormalization group analysis of the system in the Kondo regime, we find that the competition of Aharonov-Bohm and spin-orbit dynamical phases induces a strong suppression of the Kondo state singlet, somewhat akin to an effective intrinsic magnetic field in the system. This effective field breaks the spin degeneracy of the localized state and produces a finite magnetic moment in the dot. By introducing an {\em in-plane} Zeeman field we show that the Kondo resonance can be fully restored, reestablishing the spin singlet and a desired spin filtering behavior in the Kondo regime, which may result in full spin polarization of the current through the ring.