Regensburg 2025 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 17: 2D Semiconductors and van der Waals Heterostructures III

HL 17.6: Talk

Tuesday, March 18, 2025, 10:45–11:00, H15

Electric field control of the proximity-induced spin-orbit gap in bilayer graphene/WSe2 quantum dots — •Hubert Dulisch^{1, 2}, David Emmerich^{1, 2}, Eike Icking^{1, 2}, Katrin Hecker^{1, 2}, Samuel Möller^{1, 2}, Leonie Müller^{1, 2}, Kenji Watanabe³, Takashi Taniguchi⁴, Christian Volk^{1, 2}, and Christoph Stampfer^{1, 2} — ¹2nd Institute of Physics, RWTH Aachen — ²PGI-9, Forschungszentrum Jülich — ³Research Center for Functional Materials, NIMS, — ⁴International Center for Materials Nanoarchitectonics, NIMS

We investigated induced spin-orbit coupling (SOC) in a bilayer graphene (BLG) quantum dot (QD), which is in proximity to tungsten diselenide (WSe₂). Magneto-transport measurements were performed on the Coulomb-resonance of the first charge carrier to extract the spin-orbit gap Δ_SO. In-plane magnetic field measurements indicate an increased SOC-induced energy splitting. Out-of-plane field measurements demonstrate a reduced valley g-factor at larger displacement fields, consistent with weaker lateral confinement of the QD wavefunction. Our measurements reveal an enhanced SOC effect that decreases with the applied displacement field, distinguishing it from the behavior observed in pure BLG. We interpret this as a reduced influence of the WSe₂, which we attribute to the increased displacement field. This causes the QD to become more localized in the lower layer of the bilayer graphene. Being farther from the WSe₂, this layer experiences reduced induced SOC, leading to a diminished spin-orbit gap in the BLG QD.

Keywords: spin-orbit coupling; quantum dots; bilayer graphene; WSe2