发表机构
National University of Singapore; Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST; ICREA–Institució Catalana de Recerca i Estudis Avançats; Institute of Materials Research & Engineering (IMRE), Agency for Science, Technology and Research (A*STAR); Centre for Quantum Technologies, National University of Singapore; University of Manchester; Department of Physics, National University of Singapore（新加坡国立大学; 加泰罗尼亚纳米科学和纳米技术研究所（ICN2，CSIC和BIST）; 加泰罗尼亚高级研究学院（ICREA）; 材料研究与工程学院（IMRE），科学技术研究局（A*STAR）; 新加坡国立大学量子技术中心; 曼彻斯特大学; 新加坡国立大学物理系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出在石墨烯/六方氮化硼的色散莫尔次带中，通过弱磁场诱导开放轨道产生强关联，观察到初期分数量子霍尔效应输运特征，开辟了超越平带范式的关联拓扑态新路径。
AI 中文摘要
分数量子霍尔绝缘体的实现主要依赖于具有理想量子几何的复杂双层或多层莫尔系统中孤立的平带。这些相是否能在真正色散的能带中出现，以及通过何种机制出现，仍然是一个悬而未决的问题。在此，我们提出了一种在单层石墨烯/六方氮化硼的高度色散能带中由磁场诱导强关联的机制。在第二个莫尔次带的低场经典-量子交叉区域，我们展示了莫尔势与弱磁场（B < 1.5 T）的相互作用深刻改变了电子动力学。鞍点范霍夫奇点产生延伸的开放轨道，强烈抑制载流子传播，可能有利于库仑相互作用变得相对更重要的状态，而弱磁场则解除谷简并，三角翘曲重新分布贝里曲率。高分辨率磁输运和温度依赖测量揭示了分数斜率输运特征以及相互作用驱动的不可压缩性迹象。由于霍尔电导未完全量子化且纵向电阻保持有限，我们将这些观测描述为初期的分数量子霍尔效应行为：与正在发展的分数量子霍尔绝缘态一致的输运特征，而不声称已通过完全霍尔量子化和消失的纵向电阻确立了完全发展的分数量子霍尔效应相。我们的结果表明，在经典-量子交叉区域，色散带中可能存在一条基于费米面学的路径通向关联拓扑态，这与传统的平带情景不同。
英文摘要
The realization of fractional Chern insulators has largely relied on isolated flat bands in complex bilayer or multilayer moiré systems with ideal quantum geometry. Whether such phases can emerge in genuinely dispersive bands, and by what mechanism, remains an open question. Here, we propose a mechanism for magnetic-field-induced strong correlations in the highly dispersive bands of monolayer graphene on hexagonal boron nitride. In the low-field classical-to-quantum crossover regime of the second moiré miniband, we show that the interplay of the moiré potential and weak magnetic fields (B < 1.5 T) profoundly alters electron dynamics. Saddle-point van Hove singularities produce extended open orbits that strongly suppress carrier propagation, potentially favoring a regime in which Coulomb interactions become comparatively more important, while weak magnetic fields lift valley degeneracy and trigonal warping redistributes Berry curvature. High-resolution magnetotransport and temperature-dependent measurements reveal fractional-slope transport features and signatures of interaction-driven incompressibility. Because the Hall conductivity is not fully quantized and the longitudinal resistance remains finite, we describe these observations as incipient FCI behavior: transport signatures consistent with a developing fractional Chern insulating state, without claiming a fully developed FCI phase established by complete Hall quantization and vanishing longitudinal resistance. Our results suggest a possible fermiology-driven route toward correlated topological states in dispersive bands in the classical-to-quantum crossover, distinct from the conventional flat-band scenario.
Comments23 pages, 4 figures
