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Large-angle twisted bilayer graphene (tBLG) is known to be electronically decoupled due to the spatial separation of the Dirac cones corresponding to individual graphene layers in the reciprocal space. The close spacing between the layers…

Mesoscale and Nanoscale Physics · Physics 2023-02-28 Alina Mrenca-Kolasinska , Peter Rickhaus , Giulia Zheng , Klaus Richter , Thomas Ihn , Klaus Ensslin , Ming-Hao Liu

We construct a heavy fermion representation for twisted bilayer graphene (TBG) systems. Two local orbitals (per spin/valley) are analytically found, which are exactly the maximally localized zero modes of the continuum Hamiltonian near the…

Strongly Correlated Electrons · Physics 2022-12-20 Hao Shi , Xi Dai

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…

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

We explore in detail the electronic phases of a system consisting of three non-colinear arrays of coupled quantum wires, each rotated 120 degrees with respect to the next. A perturbative renormalization-group analysis reveals that multiple…

Strongly Correlated Electrons · Physics 2020-04-29 Chuan Chen , A. H. Castro Neto , Vitor M. Pereira

Even as the understanding of the mechanism behind correlated insulating states in magic-angle twisted bilayer graphene converges towards various kinds of spontaneous symmetry breaking, the metallic "normal state" above the insulating…

Strongly Correlated Electrons · Physics 2021-12-24 Peter Cha , Aavishkar A. Patel , Eun-Ah Kim

Correlated insulators and superconductivity have been observed in "magic-angle" twisted bilayer graphene, when the nearly flat bands close to neutrality are partially filled. While a momentum-space continuum model accurately describes these…

Strongly Correlated Electrons · Physics 2019-06-04 Hoi Chun Po , Liujun Zou , T. Senthil , Ashvin Vishwanath

We identify states favored by Coulomb interactions projected onto the Wannier basis of the four narrow bands of the "magic angle" twisted bilayer graphene. At the filling of two electrons/holes per moire unit cell, such interactions favor…

Strongly Correlated Electrons · Physics 2019-06-20 Jian Kang , Oskar Vafek

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

Electrons in quantum materials exhibiting coexistence of dispersionless (flat) bands piercing dispersive (steep) bands can give rise to strongly correlated phenomena, and are associated with unconventional superconductivity. It is known…

Strongly Correlated Electrons · Physics 2020-06-01 Stephen Carr , Chenyuan Li , Ziyan Zhu , Efthimios Kaxiras , Subir Sachdev , Alex Kruchkov

Recent experiments have observed possible spin- and valley-polarized insulators and spin-triplet superconductivity in twisted double bilayer graphene, a moire structure consisting of a pair of Bernal-stacked bilayer graphene. Besides the…

Strongly Correlated Electrons · Physics 2020-08-12 Yi-Ting Hsu , Fengcheng Wu , S. Das Sarma

We address the effective tight-binding Hamiltonian that describes the insulating Mott state of twisted graphene bilayers at a magic angle. In that configuration, twisted bilayers form a honeycomb superlattice of localized states,…

Strongly Correlated Electrons · Physics 2019-06-24 Kangjun Seo , Valeri N. Kotov , Bruno Uchoa

Motivated by the recently observed insulating states in twisted bilayer graphene, we study the nature of the correlated insulating phases of the twisted bilayer graphene at commensurate filling fractions. We use the continuum model and…

Strongly Correlated Electrons · Physics 2020-07-23 Yi Zhang , Kun Jiang , Ziqiang Wang , Fuchun Zhang

Identifying the microscopic processes that limit conductivity is essential for understanding correlated and quantum-critical states in quantum materials. In twisted bilayer graphene (TBG) and other twist-controlled materials, the…

The discovery of superconducting and insulating states in magic angle twisted bilayer graphene (MATBG) has ignited considerable interest in understanding the nature of electronic interactions in this chemically pristine material system. The…

Mesoscale and Nanoscale Physics · Physics 2019-08-02 Yonglong Xie , Biao Lian , Berthold Jäck , Xiaomeng Liu , Cheng-Li Chiu , Kenji Watanabe , Takashi Taniguchi , B. Andrei Bernevig , Ali Yazdani

Interplay of strong correlation and flat topological band has been a central problem in moir\'e systems such as the magic angle twisted bilayer graphene (TBG). Recent studies show that Mott-like states may still be possible in TBG despite…

Strongly Correlated Electrons · Physics 2025-07-02 Jing-Yu Zhao , Boran Zhou , Ya-Hui Zhang

Twist bilayer graphenes with magical angle have nearly flat band, which become strongly correlated electron systems. Herein, we propose another system based on strained bilayer graphene that have flat band at the intrinsic Fermi level. The…

Mesoscale and Nanoscale Physics · Physics 2019-01-28 Ma Luo

Twisted bilayer graphene (TBG) with interlayer twist angles near the magic angle $\approx 1.08^{\circ}$ hosts flat bands and exhibits correlated states including Mott-like insulators, superconductivity and magnetism. Here we report combined…

Here we present a theoretical analysis (applicable to all twist angles of TBG) of band dispersion and density of states in TBG relating evolution of flat band and Van-Hove singularities with evolution of interlayer coupling in TBG. A simple…

Mesoscale and Nanoscale Physics · Physics 2024-08-09 Veerpal , B. R. K. Nanda , Ajay

Proximity orbital and spin-orbital effects of graphene on monolayer transition-metal dichalcogenides (TMDCs) are investigated from first-principles. The Dirac band structure of graphene is found to lie within the semiconducting gap of TMDCs…

Mesoscale and Nanoscale Physics · Physics 2016-04-27 Martin Gmitra , Denis Kochan , Petra Högl , Jaroslav Fabian