菱形四层石墨烯中的磁击穿与反常量子振荡
Magnetic Breakdown and Anomalous Quantum Oscillation in Rhombohedral Tetralayer Graphene
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中文总结 AI 辅助
研究电子掺杂菱形四层石墨烯中范霍夫奇点附近的磁击穿，识别出反常舒布尼科夫-德哈斯效应，证实其可作为费米面几何的探针，或可解释近期相关量子振荡实验。
中文摘要 AI 辅助
我们研究了电子掺杂菱形四层石墨烯中范霍夫奇点（VHSs）附近的磁击穿，该体系近期被报道存在手性超导性。利用非相互作用能带结构与久保公式，我们识别出反常的舒布尼科夫-德哈斯效应：朗道扇区中的环状结构及频谱中的反常高频峰。这些反常量子振荡可通过范霍夫奇点分隔的三个邻近费米口袋间磁击穿导致的重构来解释。值得注意的是，这些定性反常特征在更强的范霍夫奇点区域仍存在，而该区域半经典图像失效且手性超导性出现。我们还研究了振荡的温度与弱无序依赖关系。研究结果表明，磁击穿诱导的反常量子振荡是与范霍夫奇点相关的底层费米面几何的通用独特探针，或可解释近期菱形四层石墨烯中的量子振荡实验[arXiv:2606.05356]。
英文摘要
We investigate magnetic breakdown near Van Hove singularities (VHSs) in the electron-doped rhombohedral tetralayer graphene, where chiral superconductivity has recently been reported. Using the noninteracting band structure and Kubo formula, we identify anomalous Shubnikov-de Haas effects: Ring-like structures in the Landau fan and anomalous high-frequency peaks in the frequency spectra. These anomalous quantum oscillations can be understood by the reconstruction from magnetic breakdown among three nearby Fermi pockets separated by VHSs. Remarkably, these qualitative anomalous features persist into a stronger-VHS regime, where the semiclassical picture breaks down. The temperature and (weak) disorder dependence of the oscillations are also investigated. Our results establish that the magnetic-breakdown-induced anomalous quantum oscillation provides a general distinctive probe for the underlying Fermi-surface geometry associated with VHSs and may explain the recent quantum oscillation experiment in rhombohedral tetralayer graphene [arXiv:2606.05356].
