De Haas-van Alphen spectroscopy and magnetic breakdown in moiré graphene

• 成果类型: Article
• 署名作者: Bocarsly, Matan; Uzan, Matan; Roy, Indranil; Grover, Sameer; Xiao, Jiewen; Dong, Zhiyu; Labendik, Mikhail; Uri, Aviram; Huber, Martin E.; Myasoedov, Yuri; Watanabe, Kenji; Taniguchi, Takashi; Yan, Binghai; Levitov, Leonid S.; Zeldov, Eli
• 署名单位: Weizmann Institute of Science; Massachusetts Institute of Technology (MIT); University of Colorado System; University of Colorado Denver; Children's Hospital Colorado; University of Colorado Anschutz Medical Campus; National Institute for Materials Science; National Institute for Materials Science
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-9628
• DOI: 10.1126/science.adh3499
• 发表日期: 2024-01-05
• 页码: 42-48
• 关键词: correlated states; dirac fermions; electron-gas; squid; oscillations; bands

摘要

Quantum oscillations originating from the quantization of electron cyclotron orbits provide sensitive diagnostics of electron bands and interactions. We report on nanoscale imaging of the thermodynamic magnetization oscillations caused by the de Haas-van Alphen effect in moire graphene. Scanning by means of superconducting quantum interference device (SQUID)-on-tip in Bernal bilayer graphene crystal axis-aligned to hexagonal boron nitride reveals large magnetization oscillations with amplitudes reaching 500 Bohr magneton per electron in weak magnetic fields, unexpectedly low frequencies, and high sensitivity to superlattice filling fraction. The oscillations allow us to reconstruct the complex band structure, revealing narrow moire bands with multiple overlapping Fermi surfaces separated by unusually small momentum gaps. We identified sets of oscillations that violate the textbook Onsager Fermi surface sum rule, signaling formation of broad-band particle-hole superposition states induced by coherent magnetic breakdown.