Theory of tunneling spectra for a few-electron bilayer graphene quantum dot

TL;DR

This paper investigates quantum tunneling in a few-electron bilayer graphene quantum dot, revealing how to identify electron states and their splittings due to interactions and magnetic fields, aiding future quantum device development.

Contribution

It introduces a method to distinguish single- and two-electron states' orbital, spin, and valley characteristics from conductance measurements in bilayer graphene quantum dots.

Findings

Identification of electron state compositions from conductance data.

Observation of spin and valley multiplet splittings.

Insights into spin- and valley-dependent tunneling mechanisms.

Abstract

The tuneability and control of quantum nanostructures in two-dimensional materials offer promising perspectives for their use in future electronics. It is hence necessary to analyze quantum transport in such nanostructures. Material properties such as a complex dispersion, topology, and charge carriers with multiple degrees of freedom, are appealing for novel device functionalities but complicate their theoretical description. Here, we study quantum tunnelling transport across a few-electron bilayer graphene quantum dot. We demonstrate how to uniquely identify single- and two-electron dot states' orbital, spin, and valley composition from differential conductance in a finite magnetic field. Furthermore, we show that the transport features manifest splittings in the dot's spin and valley multiplets induced by interactions and magnetic field (the latter splittings being a consequence of bilayer graphene's Berry curvature). Our results elucidate spin- and valley-dependent tunnelling mechanisms and will help to utilize bilayer graphene quantum dots, e.g., as spin and valley qubits.