Superconductivity with intrinsic topological order induced by pure Coulomb interaction and time-reversal symmetry breaking

Recently, in certain flat band lattice systems at commensurate fillings, fractional quantum Hall states have been found, which have anyonic excitations. We study such systems away from commensuration, i.e., the ground state of an anyon gas in such a system. The presence of the underlying lattice allows access to an entirely new regime where the anyon kinetic energy can be larger than their interaction energy. Within the flux-attachment approach, using a mean field and then adding fluctuations, we find several possible superfluid states. Two have intrinsic topological order: fractionalized quasiparticles with a fusion structure of (Z[subscript 2])[superscript 4] and (Z[subscript 8])[superscript 2], respectively, and a third has no fractionalized excitations similar to a BCS-type state. This represents a mechanism for superconductivity driven purely by strong repulsion and complex hopping of electrons.National Science Foundation (U.S.) (Grant DMR-1005541