Competing mechanisms for singlet-triplet transition in artificial molecules

TL;DR

This paper investigates how magnetic fields induce singlet-triplet transitions in two-electron quantum dot molecules, revealing mechanisms involving correlations and localization, and mapping the phase diagram for realistic devices.

Contribution

It identifies distinct mechanisms for singlet-triplet transitions depending on field direction and provides a phase diagram for practical quantum dot systems.

Findings

Mechanisms involve in-plane correlations or localization in opposite dots.

Both spin and orbital degrees of freedom are controllable via magnetic field.

Phase diagram of singlet-triplet transition in quantum dots is mapped.

Abstract

We study the magnetic field induced singlet/triplet transition for two electrons in vertically coupled quantum dots by exact diagonalization of the Coulomb interaction. We identify the different mechanisms occurring in the transition, involving either in-plane correlations or localization in opposite dots, depending on the field direction. Therefore, both spin and orbital degrees of freedom can be manipulated by field strength and direction. The phase diagram of realistic devices is determined.