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Flat bands in moir\'e superlattices provide a fertile ground for correlated and topological phases, governed by their quantum geometric properties. While the valley-based paradigm captures key features in select materials, it breaks down in…

Mesoscale and Nanoscale Physics · Physics 2026-05-19 Xiaoting Zhou , Yi-Chun Hung , Arun Bansil

Sliding is a ubiquitous phenomenon in moir\'e systems, but its direct influence on moir\'e bands, especially in multi-twist moir\'e systems, has been largely overlooked to date. Here, we theoretically show that sliding provides a unique…

Mesoscale and Nanoscale Physics · Physics 2025-09-12 Shi-Ping Ding , Miao Liang , Tian-Le Wu , Meng-Hao Wu , Jing-Tao Lü , Jin-Hua Gao , X. C. Xie

In view of a better understanding of the geometry of scalar flat K\"ahler metrics, this paper studies two families of scalar flat K\"ahler metrics constructed in [10] by A. D. Hwang and M. A. Singer on $\mathbb C^{n+1}$ and on $\mathcal…

Differential Geometry · Mathematics 2023-12-12 Simone Cristofori , Michela Zedda

Charge carriers in magic angle graphene come in eight flavors described by a combination of their spin, valley, and sublattice polarizations. When the inversion and time reversal symmetries are broken by the substrate or by strong…

We give a direct calculation of the curvature of the Hitchin connection, in geometric quantization on a symplectic manifold, using only differential geometric techniques. In particular, we establish that the curvature acts as a first-order…

Differential Geometry · Mathematics 2014-09-04 Jørgen Ellegaard Andersen , Niels Leth Gammelgaard

Here we study the systematic evolution of the topological properties of a Chern insulator in presence of an electronic dispersion that can be tuned smoothly from being Dirac-like till a semi-Dirac one and beyond. The band structure under…

Mesoscale and Nanoscale Physics · Physics 2022-03-31 Sayan Mondal , Priyadarshini Kapri , Bashab Dey , Tarun Kanti Ghosh , Saurabh Basu

We show that bilayer graphene in the presence of a 2D superlattice potential provides a highly tunable setup that can realize a variety of flat band phenomena. We focus on two regimes: (i) topological flat bands with non-zero Chern numbers,…

Mesoscale and Nanoscale Physics · Physics 2023-06-16 Sayed Ali Akbar Ghorashi , Aaron Dunbrack , Ahmed Abouelkomsan , Jiacheng Sun , Xu Du , Jennifer Cano

We develop an interpretable, data-driven framework to quantify how single-particle band geometry governs the stability of fractional Chern insulators (FCIs). Using large-scale exact diagonalization, we evaluate an FCI metric that yields a…

Strongly Correlated Electrons · Physics 2025-12-02 Oriol Mayné i Comas , André Grossi Fonseca , Sachin Vaidya , Marin Soljačić

Topological quantum states have been proposed and investigated on two-dimensional flat surfaces or lattices with different geometries like the plane, cylinder and torus. Here, we study quantum anomalous Hall (QAH) or Chern insulator (CI)…

Mesoscale and Nanoscale Physics · Physics 2018-01-24 Ai-Lei He , Wei-Wei Luo , Yi-Fei Wang , Chang-De Gong

We show that the charge conductivity for impurity free multi band electronic systems can be expressed in terms of the diagonal and non-diagonal elements of the Zitterbewegung amplitudes while the Berry curvature and the Chern number is…

Mesoscale and Nanoscale Physics · Physics 2010-11-11 József Cserti , Gyula Dávid

Topological band theory establishes a standardized framework for classifying different types of topological matters. Recent investigations have shown that hyperbolic lattices in non-Euclidean space can also be characterized by hyperbolic…

Mesoscale and Nanoscale Physics · Physics 2023-03-22 Weixuan Zhang , Fengxiao Di , Xingen Zheng , Houjun Sun , Xiangdong Zhang

In this article we continue the study of the two curvature notions for K\"ahler manifolds introduced by the first named author earlier: the so-called cross quadratic bisectional curvature (CQB) and its dual ($^d$CQB). We first show that…

Differential Geometry · Mathematics 2025-03-18 Lei Ni , Fangyang Zheng

We investigate the Bloch bands and develop a linear response theory for nonlinear systems, where the interplay between topological parameters and nonlinearity leads to new band structures. The nonlinear system under consideration is…

Quantum Physics · Physics 2022-10-26 Fude Li , Junjie Wang , Dianzhen Cui , K. Xue , X. X. Yi

The semiclassical quantization of cyclotron orbits for two-dimensional Bloch electrons in a coupled two band model with a particle-hole symmetric spectrum is considered. As concrete examples, we study graphene (both mono and bilayer) and…

Mesoscale and Nanoscale Physics · Physics 2015-05-19 J. N. Fuchs , F. Piechon , M. O. Goerbig , G. Montambaux

We rigorously yet concisely prove the bulk-edge correspondence for general $d$-dimensional ($d$D) topological insulators in complex Altland-Zirnbauer classes, which states that the bulk topological number equals to the edge-mode index.…

Mesoscale and Nanoscale Physics · Physics 2024-11-05 Zixian Zhou , Liang-Liang Wan

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…

On a Kahler manifold there is a clear connection between the complex geometry and underlying Riemannian geometry. In some ways, this can be used to characterize the Kahler condition. While such a link is not so obvious in the non-Kahler…

Differential Geometry · Mathematics 2016-06-23 Michael G. Dabkowski , Michael T. Lock

We extend Tsuji's iterative construction of complete K\"ahler--Einstein metrics with negative scalar curvature to noncompact K\"ahler manifolds with bounded geometry, using Berndtsson's method from the compact setting. Consequently, given a…

Differential Geometry · Mathematics 2026-01-13 Quang-Tuan Dang , Tat Dat Tô

Enhancing the many-body gap of a fractional state is crucial for realizing robust fractional excitations. For fractional Chern insulators, existing studies suggest that making flat Chern bands closely resemble the lowest Landau level (LLL)…

Strongly Correlated Electrons · Physics 2025-11-25 Yitong Zhang , Siddhartha Sarkar , Xiaohan Wan , Daniel E. Parker , Shi-Zeng Lin , Kai Sun

The absence of a well-defined Fermi surface in flat-band systems challenges the conventional understanding of instabilities toward Landau order based on nesting. We investigate the existence of an intrinsic nesting structure encoded in the…

Strongly Correlated Electrons · Physics 2026-05-06 Jia-Xin Zhang , Wen O. Wang , Leon Balents , Lucile Savary