paper

Evolution of the 7/2 fractional quantum Hall state in two-subband systems

arXiv:1109.1491 · doi:10.1103/PhysRevLett.107.266802

Abstract

We report the evolution of the fractional quantum Hall state (FQHS) at even-denominator filling factor in wide GaAs quantum wells in which electrons occupy two electric subbands. The data reveal subtle and distinct evolutions as a function of density, magnetic field tilt-angle, or symmetry of the charge distribution. When the charge distribution is strongly asymmetric, there is a remarkable persistence of a resistance minimum near when two Landau levels belonging to the two subbands cross at the Fermi energy. The field position of this minimum tracks the 5/2 filling of the symmetric subband, suggesting a pinning of the crossing levels and a developing 5/2 FQHS in the symmetric subband even when the antisymmetric level is partially filled.

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