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Electron bands in the untwisted bilayer graphene flatten out in a transverse electric field, offering a promising platform for correlated electron physics. We predict that the spin/valley isospin magnetism, resembling that seen in moir\'{e}…

Mesoscale and Nanoscale Physics · Physics 2023-02-07 Zhiyu Dong , Margarita Davydova , Olumakinde Ogunnaike , Leonid Levitov

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

We investigate the topological properties of photon-dressed energy bands in bilayer $\alpha-T_{3}$ lattices under off-resonant circularly polarized light, focusing on aligned and cyclic stacking configurations. Analytical expressions for…

Mesoscale and Nanoscale Physics · Physics 2025-11-06 O. Benhaida , E. H. Saidi , L. B. Drissi , R. Ahl Laamara

Twisted bilayer graphene (TBG) provides a unique framework to elucidate the interplay between strong correlations and topological phenomena in two-dimensional systems. The existence of multiple electronic degrees of freedom -- charge, spin,…

Strongly Correlated Electrons · Physics 2021-01-27 Yuan Da Liao , Jian Kang , Clara N. Breiø , Xiao Yan Xu , Han-Qing Wu , Brian M. Andersen , Rafael M. Fernandes , Zi Yang Meng

Recent experiments on twisted bilayer graphene show an anomalous quantum Hall (AQH) effect at filling of $3$ electrons per moir\`e unit cell. The AQH effect arises in an insulating state with both valley- and ferromagnetic order. We argue,…

Strongly Correlated Electrons · Physics 2020-09-30 Thomas Bömerich , Lukas Heinen , Achim Rosch

We investigate the Twisted Bilayer Graphene (TBG) model to obtain an analytic understanding of its energetics and wavefunctions needed for many-body calculations. We provide an approximation scheme which first elucidates why the BM…

Mesoscale and Nanoscale Physics · Physics 2022-04-29 B. Andrei Bernevig , Zhi-Da Song , Nicolas Regnault , Biao Lian

The Hamiltonian of the magic-angle twisted symmetric trilayer graphene (TSTG) can be decomposed into a TBG-like flat band Hamiltonian and a high-velocity Dirac fermion Hamiltonian. We use Hartree-Fock mean field approach to study the…

Mesoscale and Nanoscale Physics · Physics 2021-10-19 Fang Xie , Nicolas Regnault , Dumitru Călugăru , B. Andrei Bernevig , Biao Lian

Electron interactions in quantum materials fundamentally shape their energy bands and, with them, the material's most intriguing quantum phases. Magic angle twisted bilayer graphene (MATBG) has emerged as a model system, where flat bands…

Mesoscale and Nanoscale Physics · Physics 2025-06-27 J. Xiao , A. Inbar , J. Birkbeck , N. Gershon , Y. Zamir , T. Taniguchi , K. Watanabe , E. Berg , S. Ilani

Rhombohedral multilayer graphene hosts a rich landscape of correlated symmetry-broken phases, driven by strong interactions from its flat band edges. Aligning to hexagonal boron nitride (hBN) creates a moir\'e pattern, leading to recent…

In twisted bilayer graphene (TBG) a moir\'e pattern forms that introduces a new length scale to the material. At the 'magic' twist angle of 1.1{\deg}, this causes a flat band to form, yielding emergent properties such as correlated…

Twisted bilayer graphene offers a unique bilayer two-dimensional-electron system where the layer separation is only in sub-nanometer scale. Unlike Bernal-stacked bilayer, the layer degree of freedom is disentangled from spin and valley,…

We report the observation of anomalously strong 2D band in twisted bilayer graphene (tBLG) with large rotation angles under 638-nm and 532-nm visible laser excitation. The 2D band of tBLG can reach four times as opposed to two times as…

A purely electronic mechanism is proposed for the unconventional superconductivity recently observed in twisted bilayer graphene (tBG) close to the magic angle. Using the Migdal-Eliashberg framework on a one parameter effective lattice…

Mesoscale and Nanoscale Physics · Physics 2024-02-19 Gargee Sharma , Maxim Trushin , Oleg P. Sushkov , Giovanni Vignale , Shaffique Adam

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

Magic-angle twisted bilayer graphene (MA-TBG) exhibits intriguing quantum phase transitions triggered by enhanced electron-electron interactions when its flat-bands are partially filled. However, the phases themselves and their connection…

Mesoscale and Nanoscale Physics · Physics 2021-04-14 Shuang Wu , Zhenyuan Zhang , K. Watanabe , T. Taniguchi , Eva Y. Andrei

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…

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,…

Evidence of flat-band magnetism and half-metallicity in compressed twisted bilayer graphene is provided with first-principles calculations. We show that dynamic band-structure engineering in twisted bilayer graphene is possible by…

Materials Science · Physics 2019-06-05 Alejandro Lopez-Bezanilla

The recently observed unconventional ferroelectricity in AB bilayer graphene sandwiched by hexagonal Boron Nitride (hBN) presents a new platform to manipulate correlated phases in multilayered van der Waals heterostructures. We present a…

Mesoscale and Nanoscale Physics · Physics 2022-11-30 Ziyan Zhu , Stephen Carr , Qiong Ma , Efthimios Kaxiras

Anomalous Hall effect (AHE), occurring in materials with broken time-reversal symmetry, epitomizes the intricate interplay between magnetic order and orbital motions of electrons[1-4]. In two dimensional (2D) systems, AHE is always coupled…

Mesoscale and Nanoscale Physics · Physics 2025-05-08 Qingxin Li , Hua Fan , Min Li , Yinghai Xu , Junwei Song , Kenji Watanabe , Takashi Taniguchi , Hua Jiang , X. C. Xie , James Hone , Cory Dean , Yue Zhao , Jianpeng Liu , Lei Wang