title: Weakly coupled Pfaffian as a type I quantum Hall liquid.
abstract: The Pfaffian phase 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 energy 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 Pfaffians exemplify a general dichotomy between type I and type II quantum Hall fluids.
authors.affiliation: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA. sashok@princeton.edu
authors.forename: S A
authors.initials: SA
authors.lastname: Parameswaran
authors.forename: S A
authors.initials: SA
authors.lastname: Kivelson
authors.forename: S L
authors.initials: SL
authors.lastname: Sondhi
authors.forename: B Z
authors.initials: BZ
authors.lastname: Spivak