Bismuthene on a SiC substrate: A candidate for a high-temperature quantum spin Hall material

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Science  29 Jun 2017:
DOI: 10.1126/science.aai8142

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Quantum spin Hall materials hold the promise of revolutionary devices with dissipationless spin currents, but have required cryogenic temperatures owing to small energy gaps. Here we show theoretically that a room-temperature regime with a large energy gap may be achievable within a paradigm that exploits the atomic spin-orbit coupling. The concept is based on a substrate-supported monolayer of a high-Z element, and is experimentally realized as a bismuth honeycomb lattice on top of the insulator SiC(0001). Using scanning tunneling spectroscopy, we detect a gap of ~0.8 eV and conductive edge states consistent with theory. Our combined theoretical and experimental results demonstrate a concept for a quantum spin Hall wide-gap scenario, where the chemical potential resides in the global system gap, ensuring robust edge conductance.

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