scholarly journals Effect of the band structure topology on the minimal conductivity for bilayer graphene with symmetry breaking

2012 ◽  
Vol 85 (4) ◽  
Author(s):  
Gyula Dávid ◽  
Péter Rakyta ◽  
László Oroszlány ◽  
József Cserti
Keyword(s):  
Band Structure ◽  
Symmetry Breaking ◽  
Bilayer Graphene ◽  
Structure Topology

scholarly journals Strained bilayer graphene: Band structure topology and Landau level spectrum

2011 ◽  
Vol 84 (4) ◽  
Author(s):  
Marcin Mucha-Kruczyński ◽  
Igor L. Aleiner ◽  
Vladimir I. Fal’ko
Keyword(s):  
Band Structure ◽  
Landau Level ◽  
Bilayer Graphene ◽  
Structure Topology ◽  
Level Spectrum

scholarly journals Superconductivity, correlated insulators, and Wess–Zumino–Witten terms in twisted bilayer graphene

2020 ◽  
Vol 117 (47) ◽  
pp. 29543-29554
Author(s):  
Maine Christos ◽  
Subir Sachdev ◽  
Mathias S. Scheurer
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Band Structure ◽  
Symmetry Breaking ◽  
Bilayer Graphene ◽  
Flavor Symmetry ◽  
Dirac Fermions ◽  
Parent State ◽  
Comprehensive Listing ◽  
Twisted Bilayer Graphene

Recent experiments on twisted bilayer graphene have shown a high-temperature parent state with massless Dirac fermions and broken electronic flavor symmetry; superconductivity and correlated insulators emerge from this parent state at lower temperatures. We propose that the superconducting and correlated insulating orders are connected by Wess–Zumino–Witten terms, so that defects of one order contain quanta of another order and skyrmion fluctuations of the correlated insulator are a “mechanism” for superconductivity. We present a comprehensive listing of plausible low-temperature orders and the parent flavor symmetry-breaking orders. The previously characterized topological nature of the band structure of twisted bilayer graphene plays an important role in this analysis.

scholarly journals Spectroscopy of a tunable moiré system with a correlated and topological flat band

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaomeng Liu ◽  
Cheng-Li Chiu ◽  
Jong Yeon Lee ◽  
Gelareh Farahi ◽  
Kenji Watanabe ◽  
...  
Keyword(s):  
Band Structure ◽  
Twist Angle ◽  
Bilayer Graphene ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Flat Band ◽  
Correlated Electron ◽  
Partial Filling ◽  
Valley Polarization ◽  
Spectroscopic Signatures

AbstractMoiré superlattices created by the twisted stacking of two-dimensional crystals can host electronic bands with flat energy dispersion in which enhanced interactions promote correlated electron states. The twisted double bilayer graphene (TDBG), where two Bernal bilayer graphene are stacked with a twist angle, is such a moiré system with tunable flat bands. Here, we use gate-tuned scanning tunneling spectroscopy to directly demonstrate the tunability of the band structure of TDBG with an electric field and to show spectroscopic signatures of electronic correlations and topology for its flat band. Our spectroscopic experiments are in agreement with a continuum model of TDBG band structure and reveal signatures of a correlated insulator gap at partial filling of its isolated flat band. The topological properties of this flat band are probed with the application of a magnetic field, which leads to valley polarization and the splitting of Chern bands with a large effective g-factor.

scholarly journals Optical manifestations of symmetry breaking in bilayer graphene

2012 ◽  
Vol 86 (4) ◽  
Author(s):  
D. S. L. Abergel ◽  
Vladimir I. Fal'ko
Keyword(s):  
Symmetry Breaking ◽  
Bilayer Graphene
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