PIRSA:18120017

Twisted Bilayer Graphene: Moire' is Different

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}}
          }

Baskaran Ganapathy

Institute of Mathematical Sciences

Talk number
PIRSA:18120017
Talk Type
Subject
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