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Materials featuring touching points, localized states, and flat bands are of great interest in condensed matter and artificial systems due to their implications in topology, quantum geometry, superconductivity, and interactions. In this…

Mesoscale and Nanoscale Physics · Physics 2024-06-21 Camillo Tassi , Dario Bercioux

Flat-band topologies and localizations in non-interacting systems are extensively studied in different quantum and classical-wave systems. Recently, the exploration on the novel physics of flat-band localizations and topologies in…

Mesoscale and Nanoscale Physics · Physics 2023-02-08 Xiaoqi Zhou , Weixuan Zhang , Houjun Sun , Xiangdong Zhang

We construct and characterize tight binding Hamiltonians which contain a completely flat topological band made of continuum lowest Landau level wavefunctions sampled on a lattice. We find an infinite family of such Hamiltonians, with simple…

Strongly Correlated Electrons · Physics 2020-01-27 Junkai Dong , Erich Mueller

Multilayer graphene systems with a rhombohedral stacking order harbor nearly flat bands in their single-particle spectrum. We propose ansatz states to describe the surface-localized states of flat band electrons. The absence of kinetic…

Strongly Correlated Electrons · Physics 2013-04-10 Hao Wang , Jin-Hua Gao , Fu-Chun Zhang

Flat band materials such as the kagome metals or moir\'e superlattice systems are of intense current interest. Flat bands can result from the electron motion on numerous (special) lattices and usually exhibit topological properties. Their…

Strongly Correlated Electrons · Physics 2024-05-28 Joseph G. Checkelsky , B. Andrei Bernevig , Piers Coleman , Qimiao Si , Silke Paschen

We study the properties of flat-bands that appear in a heterostructure composed of strands of different widths of graphene armchair nanoribbons. One of the flat-bands is reminiscent of the one that appears in pristine armchair nanoribbons…

Mesoscale and Nanoscale Physics · Physics 2022-02-18 P. A. Almeida , L. S. Sousa , Tome M. Schmidt , G. B. Martins

A flat band is nondispersive and formed under destructive interference. Although flat bands are found in various Hermitian systems, to realize a flat band in non-Hermitian systems is an interesting task. Here, we propose a flat band in a…

Quantum Physics · Physics 2019-03-07 L. Jin

We report the presence of multiple flat bands in a class of two-dimensional (2D) lattices formed by Sierpinski gasket (SPG) fractal geometries as the basic unit cells. Solving the tight-binding Hamiltonian for such lattices with different…

Disordered Systems and Neural Networks · Physics 2018-05-02 Biplab Pal , Kush Saha

Motivated by the observation of polarization superlattices in twisted multilayers of hexagonal boron nitride ($h$-BN), we address the possibility of using these heterostructures for tailoring the properties of multilayer graphene by means…

Mesoscale and Nanoscale Physics · Physics 2023-05-29 Marta Brzezińska , Oleg V. Yazyev

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

It has long been noticed that special lattices contain single-electron flat bands (FB) without any dispersion. Since the kinetic energy of electrons is quenched in the FB, this highly degenerate energy level becomes an ideal platform to…

Strongly Correlated Electrons · Physics 2014-07-16 Zheng Liu , Feng Liu , Yong-Shi Wu

Flat-band physics has attracted much attention in recently years because of its interesting properties and important applications. Some typical lattices have been proposed to generate flat bands, such as Kagome and Lieb lattices. The flat…

Materials Science · Physics 2021-08-17 Siwen Li , Yuee Xie , Yuanping Chen

The phenomenon of flat bands pinned to the Fermi surface is analyzed on the basis of the Landau-Pitaevskii relation, which is applicable to electron systems of solids. It is shown that the gross properties of normal states of high-$T_c$…

Superconductivity · Physics 2015-05-11 V. A. Khodel , J. W. Clark , V. R. Shaginyan , M. V. Zverev

We study the ground states of cold atoms in the tight-binding bands built from p-orbitals on a two dimensional honeycomb optical lattice. The band structure includes two completely flat bands. Exact many-body ground states with on-site…

Strongly Correlated Electrons · Physics 2007-08-26 Congjun Wu , Doron Bergman , Leon Balents , S. Das Sarma

Correlated insulators and superconductivity have been observed in "magic-angle" twisted bilayer graphene, when the nearly flat bands close to neutrality are partially filled. While a momentum-space continuum model accurately describes these…

Strongly Correlated Electrons · Physics 2019-06-04 Hoi Chun Po , Liujun Zou , T. Senthil , Ashvin Vishwanath

The electronic properties of $\pi$-conjugated two-dimensional (2D) polymers near the Fermi level are determined by structural topology and chemical composition. Thus, tight-binding (TB) calculations of the corresponding fundamental network…

A major hurdle in understanding the phase diagram of twisted bilayer graphene (TBLG) are the roles of lattice relaxation and electronic structure on isolated band flattening near magic twist angles. In this work, the authors develop an…

Mesoscale and Nanoscale Physics · Physics 2024-03-28 Shivesh Pathak , Tawfiqur Rakib , Run Hou , Andriy Nevidomskyy , Elif Ertekin , Harley T. Johnson , Lucas K. Wagner

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

Multiple gaps in the tight-binding band of a pentagonal lattice are found. Unlike the Cairo pentagonal lattice this lattice is made of irregular pentagons with arms of different lengths. The tight-binding Hamiltonian is exactly solved to…

Mesoscale and Nanoscale Physics · Physics 2017-02-28 Susobhan Paul , Asim Kumar Ghosh

Dispersionless bands, such as Landau levels, serve as a good starting point for obtaining interesting correlated states when interactions are added. With this motivation in mind, we study a variety of dispersionless ("flat") band structures…

Strongly Correlated Electrons · Physics 2013-05-29 Dmitry Green , Luiz Santos , Claudio Chamon