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We initiate the mathematical study of the Bistritzer-MacDonald Hamiltonian for twisted trilayer graphene in the chiral limit (and beyond). We develop a spectral theoretic approach to investigate the presence of flat bands under specific…

Mathematical Physics · Physics 2023-08-22 Simon Becker , Tristan Humbert , Jens Wittsten , Mengxuan Yang

We prove that in the chiral limit of the Bistritzer--MacDonald Hamiltonian, there exist magic angles at which the Hamiltonian exhibits flat bands of multiplicity four instead of two. We analyse the structure of Bloch functions associated…

Mathematical Physics · Physics 2025-05-13 Simon Becker , Tristan Humbert , Maciej Zworski

We demonstrate the generic existence of Dirac cones in the full Bistritzer--MacDonald Hamiltonian for twisted bilayer graphene. Its complementary set, when Dirac cones are absent, is the set of magic angles. We show the stability of magic…

Mathematical Physics · Physics 2024-07-10 Simon Becker , Solomon Quinn , Zhongkai Tao , Alexander Watson , Mengxuan Yang

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

Why do experiments only observe one magic angle in twisted bilayer graphene, despite standard models like the chiral limit of the Bistritzer-MacDonald Hamiltonian predicting an infinite number? In this article, we explore the relative…

Mathematical Physics · Physics 2025-08-15 Simon Becker , Izak Oltman , Martin Vogel

At certain angles of rotation called `magic angles' twisted bilayer graphene features almost flat bands. The resulting strong correlations drive the system to novel phases which have been observed in experiments recently. A complete…

Mesoscale and Nanoscale Physics · Physics 2018-11-01 Steven C. Carter , Hridis K. Pal , M. Kindermann

Recent experiments discovered fractional Chern insulator states at zero magnetic field in twisted bilayer MoTe$_2$ [C23,Z23] and WSe$_2$ [MD23]. In this article, we study the MacDonald Hamiltonian for twisted transition metal…

Mathematical Physics · Physics 2024-01-12 Simon Becker , Mengxuan Yang

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

In this article we study the Bistritzer-MacDonald (BM) model with external magnetic field. We study the spectral properties of the Hamiltonian in an external magnetic field with a particular emphasis on the flat band of the chiral model at…

Mathematical Physics · Physics 2024-01-05 Simon Becker , Xiaowen Zhu

Twisted bilayer graphene (TBG) has extraordinary electronic properties at the magic angle along with an isolated flat band at the magic angle. However, the non-Hermitian phenomena in twisted bilayer graphene remain unexplored. In this work,…

Mesoscale and Nanoscale Physics · Physics 2025-02-17 Yingyi Huang

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

Twisted bilayer graphene (TBG) features strongly correlated and topological phases due to its flat bands emerging near the magic angle. However, the effects of the non-Hermiticity, arising from the coupling to the environment and…

Mesoscale and Nanoscale Physics · Physics 2025-06-06 Juan Pablo Esparza , Vladimir Juricic

Twisted bilayer graphene exhibits isolated, relatively flat electronic bands near charge neutrality when the interlayer rotation is tuned to specific magic angles. These small misalignments, typically below 1.1{\deg}, result in long-period…

Mesoscale and Nanoscale Physics · Physics 2026-03-26 Antonio Palamara , Michele Pisarra , Antonello Sindona

Flat band electronic modes in twisted graphene bilayers are responsible for superconducting and other highly correlated electron-electron phases. Although some hints were known of a possible connection between the quantum Hall effect and…

Mesoscale and Nanoscale Physics · Physics 2023-05-10 Leonardo A. Navarro-Labastida , Gerardo G. Naumis

The chiral Hamiltonian for twisted graphene bilayers is written as a $2\times2$ matrix operator by a renormalization of the Hamiltonian that takes into account the particle-hole symmetry. This results in an effective Hamiltonian with an…

Mesoscale and Nanoscale Physics · Physics 2023-08-01 Gerardo G. Naumis , Leonardo A. Navarro-Labastida , Enrique Aguilar-Méndez , Abdiel Espinosa-Champo

Magic angle twisted bilayer graphene has emerged as a powerful platform for studying strongly correlated electron physics, owing to its almost dispersionless low-energy bands and the ability to tune the band filling by electrostatic gating.…

Mesoscale and Nanoscale Physics · Physics 2021-07-21 Nikhil Tilak , Xinyuan Lai , Shuang Wu , Zhenyuan Zhang , Mingyu Xu , Raquel de Almeida Ribeiro , Paul C Canfield , Eva Y. Andrei

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

We report the discovery of a series of non-equilibrium magic angles at which isolated topological flat quasienergy bands form in AA-stacked twisted multilayer graphene under circularly polarized light. These non-equilibrium magic angles can…

Strongly Correlated Electrons · Physics 2025-03-05 Yantao Li , Wang-Kong Tse

We study tunneling of charge carriers in single- and bilayer graphene. We propose an explanation for non-zero "magic angles" with 100% transmission for the case of symmetric potential barrier, as well as for their almost-survival for…

Mesoscale and Nanoscale Physics · Physics 2015-10-14 V. Kleptsyn , A. Okunev , I. Schurov , D. Zubov , M. I. Katsnelson

We investigate magnetic instabilities in charge-neutral twisted bilayer graphene close to so-called "magic angles" using a combination of real-space Hartree-Fock and dynamical mean-field theories. In view of the large size of the unit cell…

Strongly Correlated Electrons · Physics 2021-12-08 Javad Vahedi , Robert Peters , Ahmed Missaoui , Andreas Honecker , Guy Trambly de Laissardière
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