Probing Two-Electron Multiplets in Bilayer Graphene Quantum Dots

S Möller; L Banszerus; A Knothe; C Steiner; E Icking; S Trellenkamp; F Lentz; K Watanabe; T Taniguchi; L I Glazman; V I Fal'ko; C Volk; C Stampfer

doi:10.1103/PhysRevLett.127.256802

Probing Two-Electron Multiplets in Bilayer Graphene Quantum Dots

Phys Rev Lett. 2021 Dec 17;127(25):256802. doi: 10.1103/PhysRevLett.127.256802.

Authors

S Möller^{1

2}, L Banszerus^{1

2}, A Knothe³, C Steiner¹, E Icking^{1

2}, S Trellenkamp⁴, F Lentz⁴, K Watanabe⁵, T Taniguchi⁶, L I Glazman⁷, V I Fal'ko^{3

8

9}, C Volk^{1

2}, C Stampfer^{1

2}

Affiliations

¹ JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.
² Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany.
³ National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom.
⁴ Helmholtz Nano Facility, Forschungszentrum Jülich, Jülich 52425, Germany.
⁵ Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
⁶ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
⁷ Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA.
⁸ Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
⁹ Henry Royce Institute for Advanced Materials, University of Manchester, Manchester M13 9PL, United Kingdom.

PMID: 35029428
DOI: 10.1103/PhysRevLett.127.256802

Abstract

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 ≈ 0.4-0.8 meV from orbital antisymmetric states. The symmetric multiplet exhibits an additional energy splitting of its six states of ≈ 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.