Starts 30 Nov 2018 11:30
Ends 30 Nov 2018 12:30
Central European Time
SISSA, Via Bonomea 265, room 131
Single layer graphene hides manybody physics, Bilayer graphene, with AA and AB registry, exposes some of them. Twist springs more surprises. A theory [1] for superconductivity seen after tiny commensurate twists in bilayer graphene is discused. We invoke resonating valence bond (RVB) pairing contained in the dense p-pi electron fluid in graphene. RVB pairing fails to produce superconductivity in neutral graphene, as electron density of states vanish at the Fermi level. In a twisted bilayer, interlayer tunneling adds equal number of electrons and holes in regions of dominant AA registry. Self doped carriers use RVB pairing and develop charge -2e and +2e Cooper pair correlations, in spite of Coulomb repulsion. Resulting periodic superlattice 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