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arXiv · 2103.04825

Spin-valley coupling in single-electron bilayer graphene quantum dots

Luca Banszerus·Samuel Möller·Corinne Steiner·Eike Icking·Stefan Trellenkamp·Florian Lentz·Kenji Watanabe·Takashi Taniguchi·Christian Volk·Christoph Stampfer
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Abstract

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 $\approx 65~\mu$eV. Also, we find an upper limit of a potentially disorder-induced mixing of the $K$ and $K'$ states below $20~\mu$eV.

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Luca Banszerus, Samuel Möller, Corinne Steiner, Eike Icking, Stefan Trellenkamp, Florian Lentz, Kenji Watanabe, Takashi Taniguchi, Christian Volk, Christoph Stampfer. 2021-03-08. Spin-valley coupling in single-electron bilayer graphene quantum dots. https://doi.org/10.1038/s41467-021-25498-3

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