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At the interface of van der Waals heterostructures, the crystal symmetry and the electronic structure can be reconstructed, giving rise to physical properties superior to or absent in parent materials. Here by studying a Bernal bilayer graphene moiré superlattice encapsulated by 30°-twisted boron nitride flakes, we report an unprecedented ferroelectric polarization with the areal charge density up to 1013 cm-2, which is far beyond the capacity of a moiré band. The translated polarization ~5 pC m-1 is among the highest interfacial ferroelectrics engineered by artificially stacking van der Waals crystals. The gate-specific ferroelectricity and co-occurring anomalous screening are further visualized via Landau levels, and remain robust for Fermi surfaces outside moiré bands, confirming their independence on correlated electrons. We also find that the gate-specific resistance hysteresis loops could be turned off by the other gate, providing an additional control knob. Furthermore, the ferroelectric switching can be applied to intrinsic properties such as topological valley current. Overall, the gate-specific ferroelectricity with strongly enhanced charge polarization may encourage more explorations to optimize and enrich this novel class of ferroelectricity, and promote device applications for ferroelectric switching of various quantum phenomena.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: Ferroelectric polarization, bilayer graphene, Landau levels

刊行年月日: 2022-10-21

出版者: Springer Science and Business Media LLC

掲載誌:

• Nature Communications (ISSN: 20411723) vol. 13 issue. 1 6241

研究助成金:

• Natural Science Foundation of Beijing Municipality Z190011
• National Key R&D Program of China

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1038/s41467-022-34104-z

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更新時刻: 2025-02-27 16:30:30 +0900

MDRでの公開時刻: 2025-02-27 16:30:30 +0900