Interplay between tunneling and exchange effects in the two electron double quantum dot molecule

TL;DR

This paper studies how tunneling, exchange, and Coulomb interactions influence the electronic states of a two-electron double quantum dot, revealing a transition between spin states without magnetic fields.

Contribution

It introduces a comprehensive analysis including tunneling, exchange, and Coulomb effects, showing their interplay causes a spin state transition in double quantum dots.

Findings

Coulomb interaction affects tunneling behavior.

Interplay leads to a spin-singlet to spin-triplet transition.

Transition occurs without external magnetic field.

Abstract

The electronic structure of two vertically coupled quantum dots containing two electrons is investigated in the presence of interdot tunneling. Our approach also includes the interdot exchange and we find that the tunneling is affected by the Coulomb interaction. There is an interplay between direct tunneling, the interdot exchange and the Coulomb interaction influence on the tunneling, which can lead to a zero angular momentum spin-singlet - spin-triplet transition of the ground state, even in the absence of a magnetic field.