Proposed Quantum Twisting Scanning Probe Microscope over Twisted Bilayer Graphene.

Ke, Yifan; Wan, Lingyun; Qin, Xinming; Hu, Wei; Yang, Jinlong · Nano Lett · 2024

basic_science · Level V

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Abstract

Twisted bilayer graphene (TBG) has the natural merits of tunable flat bands and localized states distributed as a triangular lattice. However, the application of this state remains obscure. By density functional theory (DFT) and <i>p</i><sub><i>z</i></sub> orbital tight-binding model calculations, we investigate the tip-shaped electrostatic potential of top valence electrons of TBG at half filling. Adsorption energy scanning of molecules above the TBG reveals that this tip efficiently attracts molecules selectively to AA-stacked or AB-stacked regions. Tip shapes can be controlled by their underlying electronic structure, with electrons of low bandwidth exhibiting a more localized feature. Our results indicate that TBG tips offer applications in noninvasive and nonpolluting measurements in scanning probe microscopy and theoretical guidance for 2D material-based probes.