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Fractional Chern insulators (FCIs) are lattice analogues of fractional quantum Hall states that may provide a new avenue toward manipulating non-abelian excitations. Early theoretical studies have predicted their existence in systems with…

Recent experiments on multilayer graphene systems have rekindled interest in electronic crystal phases in two dimensions -- but now for phases enriched by non-trivial quantum geometry. In this work, we introduce a simple continuum model…

Strongly Correlated Electrons · Physics 2026-01-27 Félix Desrochers , Joe Huxford , Mark R. Hirsbrunner , Yong Baek Kim

Strongly coupling materials to cavity fields can affect their electronic properties altering the phases of matter. We study the monolayer graphene whose electrons are coupled to both left and right circularly polarized photons, and…

Mesoscale and Nanoscale Physics · Physics 2024-11-26 Ceren B. Dag , Vasil Rokaj

Over the past three decades, graphene has become the prototypical platform for discovering unique phases of topological matter. Both the Chern insulator $C\in\mathbb{Z}$ and the quantum spin Hall insulator $\nu\in\mathbb{Z}_2$ were first…

Mesoscale and Nanoscale Physics · Physics 2021-08-11 Todd Van Mechelen , Zubin Jacob

Topological invariants are global properties of the ground-state wave function, typically defined as winding numbers in reciprocal space. Over the years, a number of topological markers in real space have been introduced, allowing to map…

Mesoscale and Nanoscale Physics · Physics 2024-01-17 Nicolas Baù , Antimo Marrazzo

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

The rapid development of moir\'e quantum matter has recently led to the remarkable discovery of the fractional quantum anomalous Hall effect, and sparked predictions of other novel correlation-driven topological states. Here, we investigate…

Graphene-based moire superlattices provide a versatile platform for exploring novel correlated and topological electronic states, driven by enhanced Coulomb interactions within flat bands. The intrinsic tunability of graphene s multiple…

Strongly Correlated Electrons · Physics 2024-12-16 Jian Zheng , Size Wu , Kai Liu , Bosai Lyu , Shuhan Liu , Yating Sha , Zhengxian Li , Kenji Watanabe , Takashi Taniguchi , Jinfeng Jia , Zhiwen Shi , Guorui Chen

Berry curvature that describes local geometrical properties of energy bands can elucidate many fascinating phenomena in solid-state, photonic, and phononic systems, given its connection to global topological invariants such as the Chern…

Optics · Physics 2024-02-21 Xuefan Yin , Ye Chen , Xiaoyu Zhang , Zixuan Zhang , Susumu Noda , Chao Peng

Sixty years ago, Karplus and Luttinger pointed out that quantum particles moving on a lattice could acquire an anomalous transverse velocity in response to a force, providing an explanation for the unusual Hall effect in ferromagnetic…

The modern theory of orbital magnetization (OM) was developed by using Wannier function method, which has a formalism similar with the Berry phase. In this manuscript, we perform a numerical study on the fate of the OM under disorder, by…

Mesoscale and Nanoscale Physics · Physics 2020-07-22 Si-Si Wang , Yan-Yang Zhang , Ji-Huan Guan , Yan Yu , Yang Xia , Shu-Shen Li

In recent years, correlated insulating states, unconventional superconductivity, and topologically non-trivial phases have all been observed in several moir\'e heterostructures. However, understanding of the physical mechanisms behind these…

We propose a minimal model starting from a parent Chern band with quartic dispersion that can describe the spin-valley polarized electrons in rhombohedral tetralayer graphene. The interplay between repulsive and attractive interactions on…

Strongly Correlated Electrons · Physics 2026-05-15 Yan-Qi Wang , Zhi-Qiang Gao , Hui Yang

Electron doped rhombohedral multilayer graphene at high displacement field features an exceptionally flat band minimum with near-ideal quantum geometry. Experiments in this regime observe the formation of a 'quarter metal,' in which the…

Results are presented for Floquet systems in two spatial dimensions where the Floquet driving breaks an effective time reversal symmetry. The driving protocol also induces flat bands that correspond to anomalous Floquet phases where the…

Mesoscale and Nanoscale Physics · Physics 2022-07-15 Ceren B. Dag , Aditi Mitra

It is commonly believed that nonuniform Berry curvature destroys the Girvin-MacDonald-Platzman algebra and as a consequence destabilizes fractional Chern insulators. In this work we disprove this common lore by presenting a theory for all…

Mesoscale and Nanoscale Physics · Physics 2023-09-26 Jie Wang , Semyon Klevtsov , Zhao Liu

Topological properties lie at the heart of many fascinating phenomena in solid state systems such as quantum Hall systems or Chern insulators. The topology can be captured by the distribution of Berry curvature, which describes the geometry…

Quantum Gases · Physics 2016-05-31 N. Fläschner , B. S. Rem , M. Tarnowski , D. Vogel , D. -S. Lühmann , K. Sengstock , C. Weitenberg

We propose that the electronic structure of twisted bilayer graphene (TBG) can be understood as Dirac fermions coupled with opposite pseudo magnetic fields generated by the moir\'e pattern. The two low-energy flat bands from each monolayer…

Mesoscale and Nanoscale Physics · Physics 2019-04-24 Jianpeng Liu , Junwei Liu , Xi Dai

Despite sharing a common lattice structure, monolayer M$_2$X$_2$ compounds realize quantum anomalous Hall phases with distinct Chern numbers, a striking phenomenon that has not been fully exploared. Combining first-principles calculations…

Materials Science · Physics 2025-09-09 Zujian Dai , Xudong Zhu , Lixin He

Moir\'e flat bands in rhombohedral multilayer graphene provide a platform for exploring interaction-driven topological phases, where a single isolated band often forms a Chern band. However, non-Abelian degenerate Chern bands with internal…

Mesoscale and Nanoscale Physics · Physics 2026-04-16 Taketo Uchida , Takuto Kawakami , Mikito Koshino