High-Order Fractal Quantum Oscillations in Graphene/BN Superlattices in the Extreme Doping Limit

Wu Shi, Salman Kahn, Nicolas Leconte, Takashi Taniguchi, Kenji Watanabe, Michael Crommie, Jeil Jung, Alex Zettl

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Recent studies of van der Waals (vdW) heterostructures and superlattices have shown intriguing quantum phenomena, but these have been largely explored only in the moderate carrier density regime. Here, we report the probe of high-temperature fractal Brown-Zak (BZ) quantum oscillations through magnetotransport in the extreme doping regimes by applying a newly developed electron beam doping technique. This technique gives access to both ultrahigh electron and hole densities beyond the dielectric breakdown limit in graphene/BN superlattices, enabling the observation of nonmonotonic carrier-density dependence of fractal BZ states and up to fourth-order fractal BZ features despite strong electron-hole asymmetry. Theoretical tight-binding simulations qualitatively reproduce all observed fractal BZ features and attribute the nonmonotonic dependence to the weakening of superlattice effects at high carrier densities.

Original languageEnglish
Article number186204
JournalPhysical Review Letters
Volume130
Issue number18
DOIs
StatePublished - 5 May 2023

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