Topological states in a two-dimensional metal alloy in Si surface: BiAg/Si(111)-4 x 4 surface

Article

关键词: SPIN HALL INSULATOR;    HGTE QUANTUM-WELLS;    SUPERCONDUCTIVITY;    TRANSITION;    SCHEMES;   

DOI  :  10.1103/PhysRevB.97.085422

来源: SCIE

【 摘 要 】

A bridging topological state with a conventional semiconductor platform offers an attractive route towards future spintronics and quantum device applications. Here, based on first-principles and tight-binding calculations, we demonstrate the existence of topological states hosted by a two-dimensional (2D) metal alloy in a Si surface, the BiAg/Si(111)-4 x 4 surface, which has already been synthesized experimentally. It exhibits a topological insulating state with an energy gap of 71 meV (similar to 819 K) above the Fermi level and a topological metallic state with quasiquantized conductance below the Fermi level. The underlying mechanism leading to the formation of such nontrivial states is revealed by analysis of the charge-transfer and orbital-filtering effect of the Si substrate. A minimal effective tight-binding model is employed to reveal the formation mechanism of the topological states. Our finding opens opportunities to detect topological states and measure its quantized conductance in a large family of 2D surface metal alloys, which have been or are to be grown on semiconductor substrates.

【 授权许可】

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