title: Nu = 5/2 fractional quantum Hall effect at 10 T: implications for the Pfaffian state.
abstract: We report on the magnetotransport (including tilt fields) around Landau level filling factor nu=5/2 in a high-purity modulation-doped GaAs/AlGaAs quantum well with twice the electron density of standard samples. A quantized 5/2 Hall plateau is observed at B approximately = 10 T, with an activation gap approximately 125 mK; the plateau can persist up to approximately 25 degree tilt field. This finding is discussed in the context of a proposed Moore-Read Pfaffian (or anti-Pfaffian) wave function being a possible ground state at 5/2. The tilt fields induce a background resistance at 5/2 that could be either isotropic or anisotropic, depending simply on the in-plane magnetic field direction with respect to the GaAs crystalline axis. Such data indicate a substantial coupling between the 5/2 collective phases and the GaAs crystal.
authors.affiliation: Department of Physics and Astronomy, Rice University, Houston, Texas 77251, USA.
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.forename: T
authors.initials: T
authors.lastname: Knuuttila
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Dai
authors.forename: R R
authors.initials: RR
authors.lastname: Du
authors.forename: L N
authors.initials: LN
authors.lastname: Pfeiffer
authors.forename: K W
authors.initials: KW
authors.lastname: West