PIRSA:18120017 Scientific Series Condensed Matter

DOI10.48660/18120017

Baskaran, G. (2018). Twisted Bilayer Graphene: Moire' is Different. Perimeter Institute. https://pirsa.org/18120017

Baskaran, Ganapathy. Twisted Bilayer Graphene: Moire' is Different. Perimeter Institute, Dec. 05, 2018, https://pirsa.org/18120017 

@misc{ pirsa_PIRSA:18120017,
  doi = {10.48660/18120017},
  url = {https://pirsa.org/18120017},
  author = {Baskaran, Ganapathy},
  keywords = {Condensed Matter},
  language = {en},
  title = {Twisted Bilayer Graphene: Moire{\textquoteright} is Different},
  publisher = {Perimeter Institute},
  year = {2018},
  month = {dec},
  note = {PIRSA:18120017 see, \url{https://pirsa.org}}
}

Abstract

A single layer graphene hides many body effects in the dense viscous 
fluid of p-pi electrons, Bilayer graphene, with AA and AB registry, on 
the other hand, exposes some of them. A twisted bilayer springs more 
surprises. We discuss recently seen superconductivity in twisted bilayer 
graphene. Resonating valence bond (RVB) physics contained in the dense 
electron fluid in graphene is invoked [1]. RVB fails to produce 
superconductivity in neutral graphene, as carrier are absent at the 
Fermi level. In a twisted bilayer, interlayer tunneling adds equal 
number of electron and hole carriers in Moire superlattice of dominant 
AA registry. These carriers use RVB pairing and develop charge -2e and 
+2e Cooper pair correlations, in spite of Coulomb repulsions. Resulting 
Moire lattice of Cooper pair puddles form a Josephson lattice. Coulomb 
blockade makes it a Bosonic Mott insulator. Gate voltage dopes the Bose 
Mott insulator and interesting consequences follow.

[1] G. Baskaran, arXiv:1804.00627

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