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Magic-angle ($\theta=1.05^\circ$) twisted bilayer graphene (MATBG) has shown two seemingly contradictory characters: the localization and quantum-dot-like behavior in STM experiments, and delocalization in transport experiments. We…

Strongly Correlated Electrons · Physics 2023-01-12 Zhi-Da Song , B. Andrei Bernevig

Using scanning probe microscopy and spectroscopy, we explore the spatial symmetry of the electronic wavefunctions of twisted bilayer graphene at the "magic angle" of 1.1 degrees. This small twist angle leads to a long wavelength moir\'e…

Mesoscale and Nanoscale Physics · Physics 2020-08-12 Zhiming Zhang , Rachel Myers , Kenji Watanabe , Takashi Taniguchi , Brian J. LeRoy

Magic-angle twisted bilayer graphene is the best studied physical platform featuring moire potential induced narrow bands with non-trivial topology and strong electronic correlations. Despite their significance, the Chern insulating states…

Mesoscale and Nanoscale Physics · Physics 2024-06-11 Xiaoyu Wang , Oskar Vafek

Magic-angle twisted bilayer graphene (MATBG) hosts a multitude of strongly correlated states at partial fillings of its flat bands. In a magnetic field, these flat bands further evolve into a unique Hofstadter spectrum renormalized by…

The emergence of flat bands and correlated behaviors in 'magic angle' twisted bilayer graphene (tBLG) has sparked tremendous interest, though many aspects of the system are under intense debate. Here we report observation of both…

The interplay between strong electron-electron interactions and band topology can lead to novel electronic states that spontaneously break symmetries. The discovery of flat bands in magic-angle twisted bilayer graphene (MATBG) with…

Magic-angle twisted bilayer graphene (TBG), with rotational misalignment close to 1.1$^\circ$, features isolated flat electronic bands that host a rich phase diagram of correlated insulating, superconducting, ferromagnetic, and topological…

The interplay between strong electron-electron interaction and symmetry breaking can have profound influence on the topological properties of materials. In magic angle twisted bilayer graphene (MATBG), the flat band with a single SU(4)…

The Bistritzer-MacDonald continuum model (BM model) describes the low-energy moir\'e bands for twisted bilayer graphene (TBG) at small twist angles. We derive a generalized continuum model for TBG near any commensurate twist angle, which is…

Mesoscale and Nanoscale Physics · Physics 2022-09-20 Michael G. Scheer , Kaiyuan Gu , Biao Lian

Superconductivity often occurs close to broken-symmetry parent states and is especially common in doped magnetic insulators. When twisted close to a magic relative orientation angle near 1 degree, bilayer graphene has flat moire…

Twisted bilayer graphene near the magic angle is known to have a cascade of insulating phases at integer filling factors of the low-energy bands. In this Letter we address the nature of these phases through an unrestricted, large-scale…

Strongly Correlated Electrons · Physics 2024-09-30 Khagendra Adhikari , Kangjun Seo , K. S. D. Beach , Bruno Uchoa

Twisted bilayer graphene (TBG) exhibits flat electronic bands at the so-called magic angle ($\sim 1.1^\circ$), leading to strong electron correlations and emergent quantum phases such as superconductivity and correlated insulating states.…

Mesoscale and Nanoscale Physics · Physics 2025-04-01 Ayan Mondal , Priyanka Sinha , Bheema Lingam Chittari

We analyze the electronic structure of twisted bilayer graphene (TBG) nanoribbons close to the magic angle. We describe a transition from an incomplete to a complete moir\'e structure. By considering zigzag and armchair edge terminations,…

Mesoscale and Nanoscale Physics · Physics 2023-09-14 Elias Andrade , Pierre A. Pantaleón , Francisco Guinea , Gerardo G. Naumis

Low-energy moir\'e flat bands in magic-angle twisted bilayer graphene (tBG) have demonstrated incredible potentials to exhibit rich exotic quantum phenomena. Theoretically, the moir\'e flat bands of tBG are based on the extended structures,…

Mesoscale and Nanoscale Physics · Physics 2022-05-23 Long-Jing Yin , Ling-Hui Tong , Yue-Ying Zhou , Yang Zhang , Yuan Tian , Li Zhang , Lijie Zhang , Zhihui Qin

Interactions among electrons and the topology of their energy bands can create novel quantum phases of matter. Most topological electronic phases appear in systems with weak electron-electron interactions. The instances where topological…

Mesoscale and Nanoscale Physics · Physics 2020-12-25 Kevin P. Nuckolls , Myungchul Oh , Dillon Wong , Biao Lian , Kenji Watanabe , Takashi Taniguchi , B. Andrei Bernevig , Ali Yazdani

Two monolayers of graphene twisted by a small `magic' angle exhibit nearly flat bands leading to correlated electronic states and superconductivity, whose precise nature including possible broken symmetries, remain under debate. Here we…

Strongly Correlated Electrons · Physics 2019-12-13 Jong Yeon Lee , Eslam Khalaf , Shang Liu , Xiaomeng Liu , Zeyu Hao , Philip Kim , Ashvin Vishwanath

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

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

The dominance of Coulomb interactions over kinetic energy of electrons in narrow, non-trivial moir\'{e} bands of magic-angle twisted bilayer graphene (TBG) gives rise to a variety of correlated phases such as correlated insulators,…

We study the collective excitation modes of the Chern insulator states in magic-angle twisted bilayer graphene aligned with hexagonal boron nitride (TBG/BN) at odd integer fillings ($\nu$) of the flat bands. For the $1 \times 1$…

Mesoscale and Nanoscale Physics · Physics 2023-06-07 Xianqing Lin , Quan Zhou , Cheng Li , Jun Ni