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We study strongly correlated fractional topological phases on a two-sphere threaded by a magnetic dipole field with globally vanishing flux. Solving the Dirac equation in this background produces spheroidal wavefunctions forming a highly…

Strongly Correlated Electrons · Physics 2025-07-08 Jeff Murugan

Moir\'e materials host a wealth of intertwined correlated and topological states of matter, all arising from flat electronic bands with nontrivial quantum geometry. A prominent example is the family of alternating-twist magic-angle graphene…

We show that topological frequency band structures emerge in two-dimensional electromagnetic lattices of metamaterial components without the application of an external magnetic field. The topological nature of the band structure manifests…

Strongly Correlated Electrons · Physics 2015-06-05 Vassilios Yannopapas

Topological flat bands in two-dimensional (2D) moir\'e materials have emerged as promising platforms for exploring the interplay between topology and correlation effects. However, realistic calculations of moir\'e band topology using…

Mesoscale and Nanoscale Physics · Physics 2025-11-25 Yunzhe Liu , Ethan Angerhofer , Kaijie Yang , Chao-Xing Liu , Jiabin Yu

Flat bands play an important role in the study of strongly correlated phenomena, such as ferromagnetism, superconductivity, and fractional quantum Hall effect. Here we report direct experimental evidence for the presence of flat bands,…

Mesoscale and Nanoscale Physics · Physics 2012-09-28 Lei Feng , Xianqing Lin , Lan Meng , Jia-Cai Nie , Jun Ni , Lin He

In the research of the topological band phases, the conventional wisdom is to start from the crystalline translational symmetry systems. Nevertheless, the translational symmetry is not always a necessary condition for the energy bands. Here…

Disordered Systems and Neural Networks · Physics 2025-12-03 Shuo Wang , Jing-Run Lin , Zheng-Wei Zuo

Topological flat bands (TFBs) provide a promising platform to investigate intriguing fractionalization phenomena, such as the fractional Chern insulators (FCIs). Most of TFB models are established in two-dimensional Euclidean lattices with…

Strongly Correlated Electrons · Physics 2024-08-30 Dong-Hao Guan , Lu Qi , Yuan Zhou , Ai-Lei He , Yi-Fei Wang

When electrons moving in two-dimensions (2D) are subjected to a strong uniform magnetic field, they form flat bands called Landau levels, which are the basis for the quantum Hall effect. Landau levels can also arise from pseudomagnetic…

Mesoscale and Nanoscale Physics · Physics 2025-05-14 Zheyu Cheng , Yi-jun Guan , Haoran Xue , Yong Ge , Ding Jia , Yang Long , Shou-qi Yuan , Hong-xiang Sun , Yidong Chong , Baile Zhang

Flat bands - single-particle energy bands - in tight-binding networks have attracted attention due to the presence of macroscopic degeneracies and their extreme sensitivity to perturbations. This makes them natural candidates for emerging…

Optics · Physics 2024-03-27 Carlo Danieli , Alexei Andreanov , Daniel Leykam , Sergej Flach

The construction of exponentially localized Wannier functions for a set of bands requires a choice of Bloch-like functions that span the space of the bands in question, and are smooth and periodic functions of k in the entire Brillouin…

Mesoscale and Nanoscale Physics · Physics 2016-02-03 Georg W. Winkler , Alexey A. Soluyanov , Matthias Troyer

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 construct a simple model for electrons in a three-dimensional crystal where a combination of short-range hopping and spin-orbit coupling results in nearly flat bands characterized by a non-trivial Z2 topological index. The flat band is…

Mesoscale and Nanoscale Physics · Physics 2012-01-27 C. Weeks , M. Franz

Flat bands result in a divergent density of states and high sensitivity to interactions in physical systems. While such bands are well known in systems under magnetic fields, their realization and behavior in zero-field settings remain…

Strongly Correlated Electrons · Physics 2025-08-05 Chen-Xin Jiang , Zi-Xiang Hu , Bo Yang

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

Flat bands are intriguing platforms for correlated and topological physics. Various methods have been developed to create flat bands utilizing lattice geometry, but the investigation of orbital symmetry in multiorbital materials is a new…

Strongly Correlated Electrons · Physics 2024-10-01 Keyu Zeng , Ziqiang Wang

We show how Carrollian symmetries become important in the construction of one-dimensional fermionic systems with all flat-band spectra from first principles. The key ingredient of this construction is the identification of Compact Localised…

High Energy Physics - Theory · Physics 2025-08-20 Nisa Ara , Aritra Banerjee , Rudranil Basu , Bhagya Krishnan

We present comparatively simple two-dimensional and three-dimensional checkerboard-like optical lattices possessing nontrivial topological properties. By simple tuning of the parameters these lattices can have a topological insulating…

Quantum Gases · Physics 2015-03-11 Tomi Paananen , Thomas Dahm

The results of the paper concern the topological structure of complete riemannian manifolds with cyclic holonomy groups and low-dimensional orientable complete flat manifolds. We also discuss related results such as the affine…

Differential Geometry · Mathematics 2007-05-23 M. Sadowski

The main goal of this article is to construct some geometric invariants for the topology of the set $\mathcal{F}$ of flat connections on a principal $G$-bundle $P\,\longrightarrow\, M$. Although the characteristic classes of principal…

Differential Geometry · Mathematics 2017-04-19 Indranil Biswas , Marco Castrillón López

We study the influence of spatial symmetries on the appearance and the number of exact flat bands (FBs) in single and bilayer systems with Dirac or quadratic band crossing points, and systematically classify all possible number of exact…

Mesoscale and Nanoscale Physics · Physics 2025-07-08 Siddhartha Sarkar , Xiaohan Wan , Shi-Zeng Lin , Kai Sun