paper

Partial filled Landau Level at even denominator, a vortex metal with Berry phase

arXiv:1711.03969 · doi:10.1103/PhysRevB.97.165115

Abstract

We develop a vortex metal theory for partial filled Landau Level at , whose ground state contains a composite Fermi surface(FS) formed by the vortex of electrons. In the projected Landau Level limit, the composite Fermi surface contains Berry phase. Such fractional Berry phase is a consequence of LL projection which produces the GMP guiding center algebra and embellishes an anomalous velocity to the equation of motion for the vortex metal. Further, we investigate a particle-hole symmetric bilayer system with and at each layer, and demonstrate that the Berry phase on the composite Fermi surface leads to the suppression of back-scattering between the PH partner bilayer, which could be a smoking gun to detect the fractional Berry phase. We also mention various instabilities and competing orders in such bilayer system including a topological order phase driven by quantum criticality.

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