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In 1993 Keski-Vakkuri and Wen introduced a model for the fractional quantum Hall effect based on multilayer two-dimensional electron systems satisfying quasi-periodic boundary conditions. Such a model is essentially specified by a choice of…

Algebraic Geometry · Mathematics 2025-03-11 Igor Burban , Semyon Klevtsov

Following a suggestion made by J.-P. Demailly, for each $k\ge 1$, we endow, by an induction process, the $k$-th (anti)tautological line bundle $\mathcal O_{X_k}(1)$ of an arbitrary complex directed manifold $(X,V)$ with a natural smooth…

Differential Geometry · Mathematics 2017-04-04 Simone Diverio

Perfectly flat bands with nontrivial quantum geometry have emerged as a frontier for exotic topological phenomena and superconductors. Here, we unveil a universal family of quantized Berry-dipole flat bands in chiral-symmetric (2n+1)-band…

Mesoscale and Nanoscale Physics · Physics 2026-02-05 Qingyang Mo , Shuang Zhang

We address the question of whether fractionally filled bands with a nontrivial Chern index in zero external field could also exhibit a Fractional Quantum Hall Effect (FQHE). Numerical works suggest this is possible. Analytic treatments are…

Strongly Correlated Electrons · Physics 2011-09-13 Ganpathy Murthy , R. Shankar

Topological insulators in odd dimensions are characterized by topological numbers. We prove the well-known relation between the topological number given by the Chern character of the Berry curvature and the Chern-Simons level of the low…

High Energy Physics - Theory · Physics 2020-04-15 Hidenori Fukaya , Tetsuya Onogi , Satoshi Yamaguchi , Xi Wu

The quantum geometry of Bloch wavefunctions,encoded in the Berry curvature and quantum metric, is believed to be a decisive ingredient in stabilizing fractional quantum anomalous Hall (FQAH) effect(i.e., fractional Chern insulator, FCI, at…

We consider bilayer graphene in the presence of spin orbit coupling, to assess its behavior as a topological insulator. The first Chern number $n$ for the energy bands of single and bilayer graphene is computed and compared. It is shown…

Mesoscale and Nanoscale Physics · Physics 2011-07-18 E. Prada , P. San-Jose , L. Brey , H. A. Fertig

We complete the classification of compact Hermitian manifolds admitting a flat Gauduchon connection. In particular, we establish a conjecture of Yang and Zheng, showing that apart from the cases of a flat Chern or Bismut connection, such…

Differential Geometry · Mathematics 2022-07-20 Ramiro A. Lafuente , James Stanfield

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

Topological insulators in odd dimensions are characterized by topological numbers. We prove the well-known relation between the topological number given by the Chern character of the Berry curvature and the Chern-Simons level of the low…

High Energy Physics - Lattice · Physics 2020-03-20 Hidenori Fukaya , Tetsuya Onogi , Satoshi Yamaguchi , Xi Wu

A critical result in superconductivity is that flat bands, though dispersionless, can still host nonzero superfluid weight due to quantum geometry. We show that the derivation of the mean field superfluid weight in previous literature is…

The discovery of zero-field fractional Chern insulators (FCIs) in moir\'e materials has attracted intense interest in the interplay between topology and correlations. Here, we demonstrate that fractionalized topological order can emerge…

Mesoscale and Nanoscale Physics · Physics 2025-10-20 Hui Liu , Raul Perea-Causin , Zhao Liu , Emil J. Bergholtz

By combining exotic band dispersion with nontrivial band topology, an interesting type of band structure, namely the flat chern band (FCB), has recently been proposed to spawn high-temperature fractional quantum hall states. Despite the…

Materials Science · Physics 2013-03-15 Zheng Liu , Zheng-Fei Wang , Jia-Wei Mei , Yong-Shi Wu , Feng Liu

We study how the stability of the fractional quantum Hall effect (FQHE) is influenced by the geometry of band structure in lattice Chern insulators. We consider the Hofstadter model, which converges to continuum Landau levels in the limit…

Strongly Correlated Electrons · Physics 2016-06-22 T. S. Jackson , David Bauer , Rahul Roy

Recent development on fractional Chern insulators and proximate phases call for a real space representation of isolated Chern bands. Here we propose a new method for a general construction of optimally localized Wannier functions from such…

Mesoscale and Nanoscale Physics · Physics 2024-07-15 Fang Xie , Yuan Fang , Lei Chen , Jennifer Cano , Qimiao Si

We study the dynamics of electrons in crystalline solids in the presence of inhomogeneous external electric and magnetic fields. We present a manifestly gauge-invariant operator-based approach without relying on a semiclassical wavepacket…

Mesoscale and Nanoscale Physics · Physics 2025-03-17 Chen Xu , Andreas Haller , Suraj Hegde , Tobias Meng , Thomas L. Schmidt

We present a theory of the superfluid weight in multiband attractive Hubbard models within the Bardeen-Cooper-Schrieffer (BCS) mean field framework. We show how to separate the geometric contribution to the superfluid weight from the…

Superconductivity · Physics 2017-01-30 Long Liang , Tuomas I. Vanhala , Sebastiano Peotta , Topi Siro , Ari Harju , Päivi Törmä

We propose a general principle for the low-energy theory of narrow bands with concentrated Berry curvature and Fubini-Study metric in the form of a map to Anderson-"+" models composed of heavy fermions hybridizing and interacting with…

We introduce a class of almost homogeneous varieties contained in the class of spherical varieties and containing horospherical varieties as well as complete symmetric varieties. We develop K{\"a}hler geometry on these varieties, with…

Differential Geometry · Mathematics 2020-09-16 Thibaut Delcroix

For any symmorphic magnetic space group $G$, it is proven that topological band insulators with vanishing first Chern numbers cannot have a groundstate composed of a single, energetically-isolated band. This no-go statement implies that the…

Mesoscale and Nanoscale Physics · Physics 2018-12-03 A. Alexandradinata , J. Höller
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