Nu = 5/2 fractional quantum Hall effect at 10 T: implications for the Pfaffian state.
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.
Zhang
Chi
C
Department of Physics and Astronomy, Rice University, Houston, Texas 77251, USA.
Knuuttila
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T
Dai
Yanhua
Y
Du
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Pfeiffer
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West
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KW