Abstract
We report the observation, for the first time, of a fractional quantum Hall state at ν=1/2 Landau-level filling in a low disorder, double-layer electron system realized in a 680-Å-wide GaAs/AlGaAs single quantum well. A nearly vanishing diagonal resistance and a Hall resistance quantized at 2h/ to within 0.3% are observed at ≃15 T and ≃26 mK. The activated temperature dependence of the diagonal resistance minimum yields a quasiparticle excitation energy gap of 230 mK.
- Received 21 November 1991
DOI:https://doi.org/10.1103/PhysRevLett.68.1379
©1992 American Physical Society