Probing Two-Electron Multiplets in Bilayer Graphene Quantum Dots

We report on finite bias spectroscopy measurements of the two-electron spectrum in a gate defined bilayer graphene (BLG) quantum dot for varying magnetic fields. The spin and valley degree of freedom in BLG give rise to multiplets of six orbital symmetric and ten orbital antisymmetric states. We find that orbital symmetric states are lower in energy and separated by approximate to 0.4-0.8 meV from orbital antisymmetric states. The symmetric multiplet exhibits an additional energy splitting of its six states of approximate to 0.15-0.5 meV due to lattice scale interactions. The experimental observations are supported by theoretical calculations, which allow to determine that intervalley scattering and current-current interaction constants are of the same magnitude in BLG.

Automated summary

The study finds that in bilayer graphene, orbital symmetric states have lower energy than orbital antisymmetric states, and there is a significant energy difference between them. Furthermore, the symmetric multiplet also exhibits energy splitting of its states due to lattice scale interactions.