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Magic-angle twisted bilayer graphene (MATBG) is notable as a highly tunable platform for investigating strongly correlated phenomena such as high-$T_c$ superconductivity and quantum spin liquids, due to easy control of doping level through…

Mesoscale and Nanoscale Physics · Physics 2020-06-04 Xiao Chen , Shuanglong Liu , James N Fry , Hai-Ping Cheng

We present an efficient ab initio dynamical mean-field theory (DMFT) implementation for quantitative simulations in solids. Our DMFT scheme employs ab initio Hamiltonians defined for impurities comprising the full unit cell or a supercell…

Strongly Correlated Electrons · Physics 2020-03-05 Tianyu Zhu , Zhi-Hao Cui , Garnet Kin-Lic Chan

We argue that moir\'e bilayer graphene at charge neutrality hosts a continuous semimetal-to-insulator quantum phase transition that can be accessed experimentally by tuning the twist angle between the two layers. For small twist angles near…

Mesoscale and Nanoscale Physics · Physics 2025-07-10 Jan Biedermann , Lukas Janssen

We introduce a complete physical model for the single-particle electronic structure of twisted bilayer graphene (tBLG), which incorporates the crucial role of lattice relaxation. Our model, based on $k \cdot p$ perturbation theory, combines…

Mesoscale and Nanoscale Physics · Physics 2019-08-14 Stephen Carr , Shiang Fang , Ziyan Zhu , Efthimios Kaxiras

We use self-consistent Hartree-Fock calculations performed in the full $\pi$-band Hilbert space to assess the nature of the recently discovered correlated insulator states in magic-angle twisted bilayer graphene (TBG). We find that gaps…

Strongly Correlated Electrons · Physics 2020-03-11 Ming Xie , Allan H. MacDonald

We show that the electronic structure of the low-energy bands in the small angle-twisted bilayer graphene consists of a series of semi-metallic and topological phases. In particular we are able to prove, using an approximate low-energy…

Mesoscale and Nanoscale Physics · Physics 2019-07-24 Zhida Song , Zhijun Wang , Wujun Shi , Gang Li , Chen Fang , B. Andrei Bernevig

A detailed understanding of interacting electrons in twisted bilayer graphene (tBLG) near the magic angle is required to gain insights into the physical origin of the observed broken symmetry phases. Here, we present extensive atomistic…

Mesoscale and Nanoscale Physics · Physics 2020-07-02 Zachary A. H. Goodwin , Valerio Vitale , Xia Liang , Arash A. Mostofi , Johannes Lischner

Magic-angle twisted bilayer graphene (MATBG) can host an intriguing variety of gate-tunable correlated states, including superconducting and correlated insulator states. Junction-based superconducting devices, such as Josephson junctions…

In this work we address the re-entrance of magic-angle phenomena (band flatness and quantum-geometric transport) in twisted bilayer graphene (TBG) subjected to strong magnetic fluxes $\pm \Phi_0$, $\pm 2 \Phi_0$, $\pm 3 \Phi_0$... ($\Phi_0…

Mesoscale and Nanoscale Physics · Physics 2022-10-04 Yifei Guan , Oleg V. Yazyev , Alexander Kruchkov

We study the gate voltage induced gap that occurs in graphene bilayers using \textit{ab initio} density functional theory. Our calculations confirm the qualitative picture suggested by phenomenological tight-binding and continuum models. We…

Materials Science · Physics 2007-05-23 Hongki Min , B. R. Sahu , Sanjay K. Banerjee , A. H. MacDonald

We decompose the superfluid weight D_s of magic-angle twisted bilayer graphene (MATBG) into conventional (band-velocity) and geometric (interband-coherence) contributions using a band-basis current operator splitting applied to the…

Superconductivity · Physics 2026-04-08 Jian Zhou

We develop a perturbative renormalization group (RG) theory for the topological heavy fermion (THF) model, describing magic-angle twisted bilayer graphene (MATBG) as an emergent Anderson lattice. Our theory focuses on an energy window where…

Strongly Correlated Electrons · Physics 2026-01-21 Yi Huang , Yang-Zhi Chou , Sankar Das Sarma

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

We investigate twisted double bilayer graphene (TDBG), a four-layer system composed of two AB-stacked graphene bilayers rotated with respect to each other by a small angle. Our ab initio band structure calculations reveal a considerable…

Mesoscale and Nanoscale Physics · Physics 2020-04-22 Fatemeh Haddadi , QuanSheng Wu , Alex J. Kruchkov , Oleg V. Yazyev

The superconducting (SC) state of magic-angle twisted bilayer graphene (MATBG) shows exceptional properties, as it consists of an unprecedentedly small electron (hole) ensemble of only ~ 10 power 11 carriers per square centimeter, which is…

Mesoscale and Nanoscale Physics · Physics 2024-03-05 G. Di Battista , K. C. Fong , A. Diez-Carlon , K. Watanabe , T. Taniguchi , D. K. Efetov

We review the theoretical modelling of moir\'e materials, focusing on various aspects of magic-angle twisted bilayer graphene (MA-TBG) viewed through the lens of Hartree-Fock mean-field theory. We first provide an elementary introduction to…

Strongly Correlated Electrons · Physics 2026-03-20 Yves H. Kwan , Ziwei Wang , Glenn Wagner , Nick Bultinck , Steven H. Simon , Siddharth A. Parameswaran

In magic angle twisted bilayer graphene, electron-electron interactions play a central role resulting in correlated insulating states at certain integer fillings. Identifying the nature of these insulators is a central question and…

Strongly Correlated Electrons · Physics 2020-08-19 Nick Bultinck , Eslam Khalaf , Shang Liu , Shubhayu Chatterjee , Ashvin Vishwanath , Michael P. Zaletel

We present efficient angle-dependent low-energy Hamiltonians to describe the properties of the twisted bilayer graphene (tBLG) heterostructure, based on {\it ab initio} calculations of mechanical relxation and electronic structure. The…

Mesoscale and Nanoscale Physics · Physics 2019-08-02 Shiang Fang , Stephen Carr , Ziyan Zhu , Daniel Massatt , Efthimios Kaxiras

Recently, Ref. [1] reformulated magic-angle twisted bilayer graphene (MATBG) as a topological heavy fermion problem, and used this reformulation to provide a deeper understanding for the correlated phases at integer fillings. In this work,…

Mesoscale and Nanoscale Physics · Physics 2023-08-21 Jiabin Yu , Ming Xie , B. Andrei Bernevig , Sankar Das Sarma

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