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A unique attribute of atomically thin quantum materials is the in-situ tunability of their electronic band structure by externally controllable parameters like electrostatic doping, electric field, strain, electron interactions, and displacement or twisting of atomic layers. This unparalleled control of the electronic bands has led to the discovery of a plethora of exotic emergent phenomena. But despite its key role, there is currently no versatile method for mapping the local band structure in advanced 2D materials devices in which the active layer is commonly embedded in various insulating layers and metallic gates. Utilizing a scanning superconducting quantum interference device, we image the de Haas-van Alphen quantum oscillations in a model system, the Bernal-stacked trilayer graphene with dual gates, which displays multiple highly-tunable bands. By resolving thermodynamic quantum oscillations spanning over 100 Landau levels in low magnetic fields, we reconstruct the band structure and its controllable evolution with the displacement field with unprecedented precision and spatial resolution of 150 nm. Moreover, by developing Landau level interferometry, we reveal shear-strain-induced pseudomagnetic fields and map their spatial dependence. In contrast to artificially-induced large strain, which leads to pseudomagnetic fields of hundreds of Tesla, we detect naturally occurring pseudomagnetic fields as low as 1 mT corresponding to graphene twisting by just 1 millidegree over one µm distance, two orders of magnitude lower than the typical angle disorder in high-quality twisted bilayer graphene devices. This ability to resolve the local band structure and strain on the nanoscale opens the door to the characterization and utilization of tunable band engineering in practical van der Waals devices.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: Quantum materials, local band structure, scanning superconducting quantum interference device

刊行年月日: 2023-12-14

出版者: Springer Science and Business Media LLC

掲載誌:

• Nature (ISSN: 00280836) vol. 624 issue. 7991 p. 275-281

研究助成金:

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1038/s41586-023-06763-5

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更新時刻: 2025-02-23 22:48:50 +0900

MDRでの公開時刻: 2025-02-23 22:48:50 +0900