Beyond the Flat-Band Paradigm: Open Orbits as a Route to Correlated States in Dispersive Moiré Minibands
Abstract
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.
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BibTeX
@misc{wang2026beyond,
title = {{Beyond the Flat-Band Paradigm: Open Orbits as a Route to Correlated States in Dispersive Moiré Minibands}},
author = {Zihao Wang and Pablo M. Perez-Piskunow and Calvin Pei Yu Wong and Matthew Holwill and Hao Sun and Wei Fu and Junxiong Hu and Zheng Yuntian and Zhang Xuanrui and T. Taniguchi and K. Watanabe and A. Ariando and Geliang Yu and Li Lin and Kuan Eng Johnson Goh and Stephan Roche and Jeil Jung and Kostya S. Novoselov and Nicolas Leconte},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.06110},
eprint = {2610.06110},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.06110},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Beyond the Flat-Band Paradigm: Open Orbits as a Route to Correlated States in Dispersive Moiré Minibands
AU - Zihao Wang
AU - Pablo M. Perez-Piskunow
AU - Calvin Pei Yu Wong
AU - Matthew Holwill
AU - Hao Sun
AU - Wei Fu
AU - Junxiong Hu
AU - Zheng Yuntian
AU - Zhang Xuanrui
AU - T. Taniguchi
AU - K. Watanabe
AU - A. Ariando
AU - Geliang Yu
AU - Li Lin
AU - Kuan Eng Johnson Goh
AU - Stephan Roche
AU - Jeil Jung
AU - Kostya S. Novoselov
AU - Nicolas Leconte
PY - 2026
DA - 2026/10/05
PB - arXiv
DO - 10.48550/arxiv.2610.06110
UR - https://arxiv.org/abs/2610.06110
AB - 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.
ER -