Understanding how the electron spin is coupled to orbital degrees of freedom, such as a valley degree of freedom in solid-state systems is central to applications in spin-based electronics and quantum computation. Recent developments in the preparation of electrostatically-confined quantum dots in gapped bilayer graphene (BLG) enables to study the low-energy single-electron spectra in BLG quantum dots, which is crucial for potential spin and spin-valley qubit operations. Here, we present the observation of the spin-valley coupling in a bilayer graphene quantum dot in the single-electron regime. By making use of a highly-tunable double quantum dot device we achieve an energy resolution allowing us to resolve the lifting of the fourfold spin and valley degeneracy by a Kane-Mele type spin-orbit coupling of ≈65μeV. Also, we find an upper limit of a potentially disorder-induced mixing of the K and K′ states below 20μeV.
@article{arxiv.2103.04825,
title = {Spin-valley coupling in single-electron bilayer graphene quantum dots},
author = {Luca Banszerus and Samuel Möller and Corinne Steiner and Eike Icking and Stefan Trellenkamp and Florian Lentz and Kenji Watanabe and Takashi Taniguchi and Christian Volk and Christoph Stampfer},
journal= {arXiv preprint arXiv:2103.04825},
year = {2021}
}