The Weakly Coupled Pfaffian as a Type I Quantum Hall Liquid

Categories: 
Physics - Condensed Matter (PHYS-CM)
Speaker: 
Boris Spivak, Washington State U.
Date & Time: 
March 10, 2011 - 1:30pm
Location: 
Serin E385

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, the vortices attract so that, upon varying the magnetic field from its magic value at 5/2 filling, 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.