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We propose models of twisted multilayer graphene that exhibit exactly flat Bloch bands with arbitrary Chern numbers and ideal band geometries. The models are constructed by twisting two sheets of Bernal-stacked multiple graphene layers with…

Mesoscale and Nanoscale Physics · Physics 2023-12-19 Jie Wang , Zhao Liu

A set of recent results indicates that fractionally filled bands of Chern insulators in two dimensions support fractional quantum Hall states analogous to those found in fractionally filled Landau levels. We provide an understanding of…

Strongly Correlated Electrons · Physics 2012-06-26 S. A. Parameswaran , R. Roy , S. L. Sondhi

The realization of fractional Chern insulators opens up the possibility of exploring fractionally charged excitations and anyonic statistics in the absence of a magnetic field. One of the central questions is whether lattice-based systems…

Mesoscale and Nanoscale Physics · Physics 2025-12-29 Zexu Li , Wenxuan Wang , Fajie Wang , Zaizhe Zhang , Qiu Yang , Kenji Watanabe , Takashi Taniguchi , X. C. Xie , Jie Wang , Kaihui Liu , Zhida Song , Xiaobo Lu

Ideal Chern insulating phases arise in two-dimensional systems with broken time-reversal symmetry. They are characterized by having nearly-flat bands, and a uniform quantum geometry -- which combines the Berry curvature and quantum metric…

Mesoscale and Nanoscale Physics · Physics 2022-04-18 Christian Northe , Giandomenico Palumbo , Jonathan Sturm , Christian Tutschku , Ewelina M. Hankiewicz

The realization of fractional Chern insulators in moir\'e materials has sparked the search for further novel phases of matter in this platform. In particular, recent works have demonstrated the possibility of realizing quantum anomalous…

Mesoscale and Nanoscale Physics · Physics 2025-07-29 Raul Perea-Causin , Hui Liu , Emil J. Bergholtz

Flat bands correspond to the spatial localization of a quantum particle moving in a field with discrete or continuous translational invariance. The canonical example is the flat Landau levels in a homogeneous magnetic field. Several…

Strongly Correlated Electrons · Physics 2024-09-11 Alireza Parhizkar , Victor Galitski

The flat band is a key ingredient for the realization of interesting quantum states for novel functionalities. In this work, we investigate the conditions for the flat band in both monolayer and bilayer graphene under periodic strain. We…

Mesoscale and Nanoscale Physics · Physics 2023-10-09 Xiaohan Wan , Siddhartha Sarkar , Kai Sun , Shi-Zeng Lin

When one of the graphene layers of Magic Angle Twisted Bilayer Graphene is nearly aligned with its hexagonal boron nitride substrate (a configuration dubbed TBG/hBN), the active electronic bands are nearly flat, and have a Chern number…

Strongly Correlated Electrons · Physics 2019-12-25 Cécile Repellin , T. Senthil

We report the theoretical discovery of a systematic scheme to produce topological flat bands (TFBs) with arbitrary Chern numbers. We find that generically a multi-orbital high Chern number TFB model can be constructed by considering…

Strongly Correlated Electrons · Physics 2013-01-01 Shuo Yang , Zheng-Cheng Gu , Kai Sun , S. Das Sarma

A large number of recent works point to the emergence of intriguing analogs of fractional quantum Hall states in lattice models due to effective interactions in nearly flat bands with Chern number C=1. Here, we provide an intuitive and…

Strongly Correlated Electrons · Physics 2013-01-01 Maximilian Trescher , Emil J. Bergholtz

Motivated by the higher Chern bands of twisted graphene multilayers, we consider flat bands with arbitrary Chern number $C$ with ideal quantum geometry. While $C>1$ bands differ from Landau levels, we show that these bands host exact…

Mesoscale and Nanoscale Physics · Physics 2023-07-25 Junkai Dong , Patrick J. Ledwith , Eslam Khalaf , Jong Yeon Lee , Ashvin Vishwanath

We use a lowest Landau level model to study the recent observation of an anomalous Hall effect in twisted bilayer graphene. This effective model is rooted in the occurrence of Chern bands which arise due to the coupling between the graphene…

Strongly Correlated Electrons · Physics 2020-04-28 Nick Bultinck , Shubhayu Chatterjee , Michael P. Zaletel

Topological flat bands play an essential role in inducing exotic interacting physics, ranging from fractional Chern insulators to superconductivity, in moir\'e materials. In this work, we propose a design principle for realizing topological…

Mesoscale and Nanoscale Physics · Physics 2026-02-03 Yunzhe Liu , Anoj Aryal , Kaijie Yang , Dumitru Calugaru , Zhenyao Fang , Haoyu Hu , Qimin Yan , B. Andrei Bernevig , Chao-xing Liu

Fractional quantum anomalous Hall (FQAH) effect, a lattice analogue of fractional quantum Hall effect, offers a unique pathway toward fault-tolerant quantum computation and deep insights into the interplay of topology and strong…

Mesoscale and Nanoscale Physics · Physics 2026-04-30 Wenqi Yang , Dawei Zhai , Wang Yao

Recent experiments on bilayer graphene twisted near the magic angle have observed spontaneous integer quantum Hall states in the presence of an aligned hexagonal boron nitride (hBN) substrate. These states arise from valley ferromagnetism,…

Strongly Correlated Electrons · Physics 2020-06-18 Patrick J. Ledwith , Grigory Tarnopolsky , Eslam Khalaf , Ashvin Vishwanath

Moir\'e flatbands with high Chern numbers (C>1) offer opportunities to study the fractional quantum anomalous Hall effects that go beyond the Landau level paradigm with C=1, which remain unexplored yet. Here, we target the novel topological…

We describe a systematic method to construct models of Chern insulators whose Berry curvature and the quantum volume form coincide and are flat over the Brillouin zone; such models are known to be suitable for hosting fractional Chern…

Mesoscale and Nanoscale Physics · Physics 2021-09-28 Bruno Mera , Tomoki Ozawa

According to the Onsager's semiclassical quantization rule, the Landau levels of a band are bounded by its upper and lower band edges at zero magnetic field. However, there are two notable systems where the Landau level spectra violate this…

Mesoscale and Nanoscale Physics · Physics 2021-11-17 Yoonseok Hwang , Jun-Won Rhim , Bohm-Jung Yang

Recent developments in fractional quantum Hall (FQH) physics highlight the importance of studying FQH phases of particles partially occupying energy bands that are not Landau levels. FQH phases in the regime of strong lattice effects,…

Strongly Correlated Electrons · Physics 2022-02-04 David Bauer , Spenser Talkington , Fenner Harper , Bartholomew Andrews , Rahul Roy

Two-dimensional lattice models subjected to an external effective magnetic field can form nontrivial band topologies characterized by nonzero integer band Chern numbers. In this Letter, we investigate such a lattice model originating from…

Strongly Correlated Electrons · Physics 2013-11-01 Dong Wang , Zhao Liu , Junpeng Cao , Heng Fan