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arXiv · 1911.13176

Observation of the spin-orbit gap in bilayer graphene by one-dimensional ballistic transport

L. Banszerus·B. Frohn·T. Fabian·S. Somanchi·A. Epping·M. Müller·D. Neumaier·K. Watanabe·T. Taniguchi·F. Libisch·B. Beschoten·F. Hassler·C. Stampfer
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Abstract

We report on measurements of quantized conductance in gate-defined quantum point contacts in bilayer graphene that allow the observation of subband splittings due to spin-orbit coupling. The size of this splitting can be tuned from 40 to 80 $\mu$eV by the displacement field. We assign this gate-tunable subband-splitting to a gap induced by spin-orbit coupling of Kane-Mele type, enhanced by proximity effects due to the substrate. We show that this spin-orbit coupling gives rise to a complex pattern in low perpendicular magnetic fields, increasing the Zeeman splitting in one valley and suppressing it in the other one. In addition, we observe the existence of a spin-polarized channel of 6 e$^2$/h at high in-plane magnetic field and of signatures of interaction effects at the crossings of spin-split subbands of opposite spins at finite magnetic field.

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L. Banszerus, B. Frohn, T. Fabian, S. Somanchi, A. Epping, M. Müller, D. Neumaier, K. Watanabe, T. Taniguchi, F. Libisch, B. Beschoten, F. Hassler, C. Stampfer. 2019-11-29. Observation of the spin-orbit gap in bilayer graphene by one-dimensional ballistic transport. https://doi.org/10.1103/physrevlett.124.177701

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