Coupled Dirac Fermions and Neutrino-like Oscillations in Twisted Bilayer Graphene

Nano Letters ◽  
2013 ◽  
Vol 13 (11) ◽  
pp. 5159-5164 ◽  
Author(s):  
Lede Xian ◽  
Z. F. Wang ◽  
M. Y. Chou
Keyword(s):  
Bilayer Graphene ◽  
Dirac Fermions ◽  
Twisted Bilayer Graphene

scholarly journals Moire Is Different

2021 ◽  
Vol 13 (1) ◽  
pp. 50
Author(s):  
Wenyuan Shi
Keyword(s):  
Electronic Structures ◽  
Tight Binding ◽  
Physical Property ◽  
Large Change ◽  
Bilayer Graphene ◽  
Dirac Fermion ◽  
Dirac Fermions ◽  
Graphene Layers ◽  
Flat Bands ◽  
Twisted Bilayer Graphene

Graphene, as the thinnest material ever found, exhibits unconventionally relativistic behaviour of Dirac fermions. However, unusual phenomena (such as superconductivity) arise when stacking two graphene layers and twisting the bilayer graphene. The relativistic Dirac fermion in graphene has been widely studied and understood, but the large change observed in twisted bilayer graphene (TBG) is intriguing and still unclear because only van der Waals force (vdW) interlayer interaction is added from graphene to TBG and such a very weak interaction is expected to play a negligible role. To understand such dramatic variation, we studied the electronic structures of monolayer, bilayer and twisted bilayer graphene. Twisted bilayer graphene creates different moiré patterns when turned at different angles. We proposed tight-binding and effective continuum models and thereby drafted a computer code to calculate their electronic structures. Our calculated results show that the electronic structure of twisted bilayer graphene changes significantly even by a tiny twist. When bilayer graphene is twisted at special “magic angles”, flat bands appear. We examined how these flat bands are created, their properties and the relevance to some unconventional physical property such as superconductivity. We conclude that in the nanoscopic scale, similar looking atomic structures can create vastly different electronic structures. Like how P. W. Anderson stated that similar looking fields in science can have differences in his article “More is Different”, similar moiré patterns in twisted bilayer graphene can produce different electronic structures.

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 Correlation-Induced Insulating Topological Phases at Charge Neutrality in Twisted Bilayer Graphene

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuan Da Liao ◽  
Jian Kang ◽  
Clara N. Breiø ◽  
Xiao Yan Xu ◽  
Han-Qing Wu ◽  
...  
Keyword(s):  
Bilayer Graphene ◽  
Topological Phases ◽  
Charge Neutrality ◽  
Twisted Bilayer Graphene

scholarly journals Strange metal behavior of the Hall angle in twisted bilayer graphene

2021 ◽  
Vol 103 (24) ◽  
Author(s):  
Rui Lyu ◽  
Zachary Tuchfeld ◽  
Nishchhal Verma ◽  
Haidong Tian ◽  
Kenji Watanabe ◽  
...  
Keyword(s):  
Bilayer Graphene ◽  
Hall Angle ◽  
Twisted Bilayer Graphene

scholarly journals Correlated insulators in twisted bilayer graphene

2021 ◽  
Vol 103 (12) ◽  
Author(s):  
Ipsita Mandal ◽  
Jia Yao ◽  
Erich J. Mueller
Keyword(s):  
Bilayer Graphene ◽  
Twisted Bilayer Graphene

scholarly journals Disorder in twisted bilayer graphene

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Justin H. Wilson ◽  
Yixing Fu ◽  
S. Das Sarma ◽  
J. H. Pixley
Keyword(s):  
Bilayer Graphene ◽  
Twisted Bilayer Graphene
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