The role of antisymmetric orbitals and electron-electron interactions on the two-particle spin and valley blockade in graphene double quantum dots

TL;DR

This study investigates how antisymmetric orbitals and electron-electron interactions influence spin and valley blockade phenomena in bilayer graphene double quantum dots, revealing tunable effects and underlying mechanisms through experiments and simulations.

Contribution

It provides the first detailed experimental analysis of spin and valley blockade in two-electron bilayer graphene quantum dots considering asymmetric orbitals and interactions.

Findings

Magnetic field can tune spin and valley blockade effects.

Orbital splitting and electron interactions limit blockade phenomena.

Simulations successfully identify key interdot transitions.

Abstract

We report on an experimental study of spin and valley blockade in two-electron bilayer graphene (BLG) double quantum dots (DQDs) and explore the limits set by asymmetric orbitals and electronelectron interactions. The results obtained from magnetotransport measurements on two-electron BLG DQDs, where the resonant tunneling transport involves both orbital symmetric and antisymmetric two-particle states, show a rich level spectrum. We observe a magnetic field tunable spin and valley blockade, which is limited by the orbital splitting, the strength of the electron-electron interaction and the difference in the valley g-factors between the symmetric and antisymmetric twoparticle orbital states. Our conclusions are supported by simulations based on rate equations, which allow the identification of prominent interdot transitions associated with the transition from single to two-particle states observed in the experiment.