scholarly journals Existence of the first magic angle for the chiral model of bilayer graphene

2021 ◽  
Vol 62 (9) ◽  
pp. 091502
Author(s):  
Alexander B. Watson ◽  
Mitchell Luskin
Keyword(s):  
Bilayer Graphene ◽  
Chiral Model ◽  
Magic Angle

scholarly journals Gate-defined Josephson junctions in magic-angle twisted bilayer graphene

2021 ◽  
Author(s):  
Folkert K. de Vries ◽  
Elías Portolés ◽  
Giulia Zheng ◽  
Takashi Taniguchi ◽  
Kenji Watanabe ◽  
...  
Keyword(s):  
Josephson Junctions ◽  
Bilayer Graphene ◽  
Magic Angle ◽  
Twisted Bilayer Graphene

Raman spectra of twisted bilayer graphene close to the magic angle

2D Materials ◽  
2022 ◽  
Author(s):  
Tiago Campolina Barbosa ◽  
Andreij C. Gadelha ◽  
Douglas A. A. Ohlberg ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Laser Excitation ◽  
Bilayer Graphene ◽  
Geometrical Model ◽  
Excitation Wavelength ◽  
Magic Angle ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Excitation Laser ◽  
Twisted Bilayer Graphene

Abstract In this work, we study the Raman spectra of twisted bilayer graphene samples as a function of their twist-angles (θ), ranging from 0.03º to 3.40º, where local θ are determined by analysis of their associated moiré superlattices, as imaged by scanning microwave impedance microscopy. Three standard excitation laser lines are used (457, 532, and 633 nm wavelengths), and the main Raman active graphene bands (G and 2D) are considered. Our results reveal that electron-phonon interaction influences the G band's linewidth close to the magic angle regardless of laser excitation wavelength. Also, the 2D band lineshape in the θ < 1º regime is dictated by crystal lattice and depends on both the Bernal (AB and BA) stacking bilayer graphene and strain soliton regions (SP) [1]. We propose a geometrical model to explain the 2D lineshape variations, and from it, we estimate the SP width when moving towards the magic angle.

scholarly journals Charge order and broken rotational symmetry in magic-angle twisted bilayer graphene

Nature ◽  
2019 ◽  
Vol 573 (7772) ◽  
pp. 91-95 ◽  
Author(s):  
Yuhang Jiang ◽  
Xinyuan Lai ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
Kristjan Haule ◽  
...  
Keyword(s):  
Rotational Symmetry ◽  
Charge Order ◽  
Bilayer Graphene ◽  
Magic Angle ◽  
Twisted Bilayer Graphene

scholarly journals Slave-rotor theory on magic-angle twisted bilayer graphene

2020 ◽  
Vol 101 (23) ◽  
Author(s):  
Shin-Ming Huang ◽  
Yi-Ping Huang ◽  
Ting-Kuo Lee
Keyword(s):  
Bilayer Graphene ◽  
Magic Angle ◽  
Twisted Bilayer Graphene

scholarly journals Theory of correlated insulating behaviour and spin-triplet superconductivity in twisted double bilayer graphene

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Jong Yeon Lee ◽  
Eslam Khalaf ◽  
Shang Liu ◽  
Xiaomeng Liu ◽  
Zeyu Hao ◽  
...  
Keyword(s):  
Displacement Field ◽  
Twist Angle ◽  
Vertical Displacement ◽  
Bilayer Graphene ◽  
Magic Angle ◽  
Hartree Fock ◽  
Flat Bands ◽  
Half Filling ◽  
Spin Triplet ◽  
Experimental Findings

AbstractTwo graphene monolayers twisted by a small magic angle exhibit nearly flat bands, leading to correlated electronic states. Here we study a related but different system with reduced symmetry - twisted double bilayer graphene (TDBG), consisting of two Bernal stacked bilayer graphenes, twisted with respect to one another. Unlike the monolayer case, we show that isolated flat bands only appear on application of a vertical displacement field. We construct a phase diagram as a function of twist angle and displacement field, incorporating interactions via a Hartree-Fock approximation. At half-filling, ferromagnetic insulators are stabilized with valley Chern number $${C}_{{\rm{v}}}=\pm 2$$Cv=±2. Upon doping, ferromagnetic fluctuations are argued to lead to spin-triplet superconductivity from pairing between opposite valleys. We highlight a novel orbital effect arising from in-plane fields plays an important role in interpreting experiments. Combined with recent experimental findings, our results establish TDBG as a tunable platform to realize rare phases in conventional solids.

scholarly journals Spin density wave and electron nematicity in magic-angle twisted bilayer graphene

2020 ◽  
Vol 102 (15) ◽  
Author(s):  
A. O. Sboychakov ◽  
A. V. Rozhkov ◽  
A. L. Rakhmanov ◽  
Franco Nori
Keyword(s):  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Bilayer Graphene ◽  
Magic Angle ◽  
Twisted Bilayer Graphene
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