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It is widely known that the twisted bilayer graphene (TBG) shows flat bands at magic angles, which can be well described by the effective continuum model derived by Bistritzer and MacDonald (BM). We propose in this paper a similar twisted…

Mesoscale and Nanoscale Physics · Physics 2022-04-22 Y. Soeda , K. Asaga , T. Fukui

Twisted graphene moire superlattice has been demonstrated as an exotic platform for investigating correlated states and nontrivial topology. Among the moire family, twisted double bilayer graphene (TDBG) is a tunable flat band system…

Twisted Bilayer graphene (TBG) is known to feature isolated and relatively flat bands near charge neutrality, when tuned to special magic angles. However, different criteria for the magic angle such as the vanishing of Dirac speed, minimal…

Strongly Correlated Electrons · Physics 2019-03-27 Grigory Tarnopolsky , Alex J. Kruchkov , Ashvin Vishwanath

'Magic'-angle twisted bilayer graphene has received a lot of interest due to its flat bands with potentially non-trivial topology that lead to intricate correlated phases. A spectrum with flat bands, however, does not require a twist…

Mesoscale and Nanoscale Physics · Physics 2021-07-07 Anastasiia Skurativska , Stepan S. Tsirkin , Fabian D Natterer , Titus Neupert , Mark H Fischer

Motivated by the study of flat bands in models of twisted bilayer graphene (TBG), we give abstract conditions which guarantee the existence of a discrete set of parameters for which periodic Hamiltonians exhibit flat bands. As an…

Analysis of PDEs · Mathematics 2023-09-12 Jeffrey Galkowski , Maciej Zworski

We investigate the electronic structure of a twisted multilayer graphene system forming a moir\'e pattern. We consider small twist angles separating the graphene sheets and develop a low-energy theory to describe the coupling of Dirac Bloch…

Mesoscale and Nanoscale Physics · Physics 2019-07-17 Christophe Mora , Nicolas Regnault , B. Andrei Bernevig

We consider twisted bilayer graphene on a transition metal dichalcogenide substrate, where proximity-induced spin-orbit coupling significantly alters the eight flat bands which occur near the magic angle. The resulting band structure…

Strongly Correlated Electrons · Physics 2020-12-24 Tianle Wang , Nick Bultinck , Michael P. Zaletel

Flat band electronic modes are responsible for superconductivity in twisted bilayer graphene (TBG) rotated at magic angles. From there other magic angles can be found for any multilayered twisted graphene systems. Eventually, this lead to…

Mesoscale and Nanoscale Physics · Physics 2022-12-15 Leonardo A. Navarro-Labastida , Gerardo G. Naumis

We formulate a model of relativistic fermions moving in two Euclidean dimensions based on a tight-binding model of graphene. The eigenvalue spectrum of the resulting Dirac operator is solved numerically in smooth U(1) gauge field…

High Energy Physics - Lattice · Physics 2010-04-15 Dipankar Chakrabarti , Simon Hands , Antonio Rago

We study the chirally symmetric continuum model (CS-CM) of the twisted bilayer graphene. The equation on a flat band could be interpreted as a Dirac equation on a torus in the external non-abelian magnetic field. We prove that the existence…

Strongly Correlated Electrons · Physics 2025-02-19 Fedor K. Popov , Alexey Milekhin

Flat bands correspond to the spatial localization of a quantum particle moving in a field with discrete or continuous translational invariance. The canonical example is the flat Landau levels in a homogeneous magnetic field. Several…

Strongly Correlated Electrons · Physics 2024-09-11 Alireza Parhizkar , Victor Galitski

We investigate the effects of single, multiple, and extended defects in the form of non-magnetic impurities and vacancies in twisted bilayer graphene (TBG) at and away from the magic angle, using a fully atomistic model and focusing on the…

Mesoscale and Nanoscale Physics · Physics 2023-10-09 Lucas Baldo , Tomas Löthman , Patric Holmvall , Annica M. Black-Schaffer

The unexpected discovery of superconductivity and strong electron correlation in twisted bilayer graphene (TBG), a system containing only sp electrons, is considered as one of the most intriguing developments in two-dimensional materials in…

Mesoscale and Nanoscale Physics · Physics 2025-04-22 Wei-Chen Wang , Feng-Wu Chen , Kuan-Sen Lin , Justin T. Hou , Ho-Chun Lin , Mei-Yin Chou

The interplay of topological characteristics in real space and reciprocal space can lead to the emergence of unconventional topological phases. In this Letter, we implement a novel mechanism for generating higher-Chern flat bands on the…

Strongly Correlated Electrons · Physics 2021-11-23 Yifei Guan , Oleg V. Yazyev , Alexander Kruchkov

We experimentally investigate the band structures of chirally twisted triple bilayer graphene. The new kind of moir\'e structure, formed by three pieces of helically stacked Bernal bilayer graphene, has flat bands at charge neutral point…

Mesoscale and Nanoscale Physics · Physics 2025-01-14 Wenlu Lin , Wenxuan Wang , Shimin Cao , Miao Liang , Lili Zhao , Kenji Watanabe , Takashi Taniguchi , Jinhua Gao , Jianhao Chen , Xiaobo Lu , Yang Liu

Band engineering in twisted bilayers of the five generic two-dimensional Bravais networks is demonstrated. We first derive symmetry-based constraints on the interlayer coupling, which helps us to predict and understand the shape of the…

Strongly Correlated Electrons · Physics 2019-11-13 Toshikaze Kariyado , Ashvin Vishwanath

Magic angles in the chiral model of twisted bilayer graphene are parameters for which the chiral version of the Bistritzer--MacDonald Hamiltonian exhibits a flat band at energy zero. We compute the sums over powers of (complex) magic angles…

Mathematical Physics · Physics 2023-06-02 Simon Becker , Tristan Humbert , Maciej Zworski

Twisted bilayer graphene (TBG) has been experimentally observed to exhibit almost flat bands when the twisting occurs at certain magic angles. In this letter, we report new results on the continuum model of twisted bilayer graphene and its…

Strongly Correlated Electrons · Physics 2021-04-21 Simon Becker , Mark Embree , Jens Wittsten , Maciej Zworski

Twisted bilayer graphene (TBG) is a recently discovered two-dimensional superlattice structure which exhibits strongly-correlated quantum many-body physics, including strange metallic behavior and unconventional superconductivity. Most of…

Mesoscale and Nanoscale Physics · Physics 2024-04-22 Cunyuan Jiang , Matteo Baggioli , Qing-Dong Jiang

An accurate description of the low-energy electronic bands in twisted bilayer graphene (tBLG) is of great interest due to their relation to correlated electron phases, such as superconductivity and Mott-insulator behavior at half-filling.…

Mesoscale and Nanoscale Physics · Physics 2024-04-17 Daniel Bennett , Daniel T. Larson , Louis Sharma , Stephen Carr , Efthimios Kaxiras