Antisymmetric Spin-Orbit Coupling Effect on Kondo-Induced Electric Polarization in a Triangular Triple Quantum Dot

TL;DR

This paper investigates how antisymmetric spin-orbit coupling influences the Kondo effect and electric polarization in a triangular triple quantum dot system, revealing controllable polarization and spin reconfigurations.

Contribution

It demonstrates that antisymmetric spin-orbit coupling significantly alters Kondo-induced electric polarization and spin configurations in a TTQD, a novel insight into spin-orbit effects in quantum dots.

Findings

ASO coupling reduces electric polarization in TTQD.

ASO interaction causes spin and charge reconfigurations.

Electric polarization can be controlled by ASO coupling and magnetic flux.

Abstract

We study the local antisymmetric spin-orbit (ASO) coupling effect on spin, orbital, and charge degrees of freedom for the Kondo effect in a triangular triple quantum dot (TTQD). Here, one of the three QDs is coupled to a metallic lead through electron tunneling, and a local electric polarization is induced by the Kondo effect. The ASO interaction is introduced in the other two coupled QDs on the opposite side of the lead. Generally, the ASO coupling effect is very weak and not easily detectable, but it essentially causes spin and charge reconfigurations in the TTQD through the Kondo effect. Using an extended Anderson model for the TTQD Kondo system, we elucidate that the ASO coupling gives rise to a considerable reduction of the emergent electric polarization, as a consequence of the parity mixing of molecular orbitals in the triangular loop as well as the spin-up and spin-down coupling of local electrons. The latter leads to a local diamagnetic susceptibility owing to the ASO coupled spins. We also show that the Kondo-induced electric polarization can be controlled by the ASO coupling as well as by the magnetic flux penetrating through the TTQD.