Exchange cotunneling through quantum dots with spin-orbit coupling

TL;DR

This paper explores how spin-orbit interaction influences exchange cotunneling and Kondo effects in quantum dots, revealing magnetic field-dependent asymmetries and providing insights into spin and orbital couplings.

Contribution

It demonstrates the impact of spin-orbit coupling on exchange cotunneling and Kondo phenomena, especially under finite magnetic fields, highlighting new asymmetries in conductance.

Findings

Spin-orbit interaction affects Kondo temperature at zero field.

Finite magnetic fields break time-reversal symmetry, altering models.

Conductance becomes asymmetric and angle-dependent with magnetic field.

Abstract

We investigate the effects of spin-orbit interaction (SOI) on the exchange cotunneling through a spinful Coulomb blockaded quantum dot. In the case of zero magnetic field, Kondo effect is shown to take place via a Kramers doublet and the SOI will merely affect the Kondo temperature. In contrast, we find that the breaking of time-reversal symmetry in a finite field has a marked influence on the effective Anderson, and Kondo models for a single level. The nonlinear conductance can now be asymmetric in bias voltage and may depend strongly on direction of the magnetic field. A measurement of the angle dependence of finite-field cotunneling spectroscopy thus provides valuable information about orbital, and spin degrees of freedom and their mutual coupling.