"The weakly coupled Pfaffian as a type I quantum hall liquid"

S.A. Parameswarana: S.A. Kivelsonb, S.L. Sondhia, B.Z. Spivakc; Physica B: Condensed Matter, 06/01/12.

Additional Authors: S.A. Kivelsonb, S.L. Sondhia, B.Z. Spivakc

Abstract:

The Pfaffian phase of electrons in the proximity of a half-filled Landau level is understood to be a p+ip superconductor of composite fermions. We consider the properties of this paired quantum Hall phase when the pairing scale is small, i.e. in the weak coupling, BCS, limit, where the coherence length is much larger than the charge screening length. We find that, as in a Type I superconductor, vortices attract so that, upon varying the magnetic field from its magic value at ν=5/2, the system exhibits Coulomb frustrated phase separation. We propose that the weakly and strongly coupled Pfaffian states exemplify a general dichotomy between Type I and Type II quantum Hall fluids.