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Electrons in topological flat bands can form new topological states driven by correlation effects. The pentalayer rhombohedral graphene/hexagonal boron nitride (hBN) moiré superlattice was shown to host fractional quantum anomalous Hall effect (FQAHE) at approximately 400 mK (ref.), triggering discussions around the underlying mechanism and role of moiré effects. In particular, new electron crystal states with non-trivial topology have been proposed. Here we report electrical transport measurements in rhombohedral pentalayer and tetralayer graphene/hBN moiré superlattices at electronic temperatures down to below 40 mK. We observed two more fractional quantum anomalous Hall (FQAH) states and smaller Rxx values in pentalayer devices than those previously reported. In the new tetralayer device, we observed FQAHE at moiré filling factors v = 3/5 and 2/3. With a small current at the base temperature, we observed a new extended quantum anomalous Hall (EQAH) state and magnetic hysteresis, where Rxy = h/e2 and vanishing Rxx spans a wide range of v from 0.5 to 1.3. At increased temperature or current, EQAH states disappear and partially transition into the FQAH liquid16,17,18. Furthermore, we observed displacement field-induced quantum phase transitions from the EQAH states to the Fermi liquid, FQAH liquid and the likely composite Fermi liquid. Our observations established a new topological phase of electrons with quantized Hall resistance at zero magnetic field and enriched the emergent quantum phenomena in materials with topological flat bands.

権利情報:

• In Copyright
  

  This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: https://doi.org/10.1038/s41586-024-08470-1.

キーワード: Fractional quantum anomalous Hall effect (FQAHE), Rhombohedral graphene/hBN moiré superlattice, Topological flat band

刊行年月日: 2025-01-30

出版者: Springer Science and Business Media LLC

掲載誌:

• Nature (ISSN: 00280836) vol. 637 issue. 8048 p. 1090-1095

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原稿種別: 著者最終稿 (Accepted manuscript)

MDR DOI:

公開URL: https://doi.org/10.1038/s41586-024-08470-1

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更新時刻: 2026-07-03 16:26:43 +0900

MDRでの公開時刻: 2026-07-03 18:30:19 +0900