Absence of Floating Delocalized States in a Two-Dimensional Hole Gas

Abstract

By tracking the delocalized states of the two-dimensional hole gas in a p-type GaAs/AlGaAs heterostructure as a function of magnetic field, we mapped out a phase diagram in the density-magnetic-field plane. We found that the energy of the delocalized state from the lowest Landau level flattens out as the magnetic field tends toward zero. This finding is different from that for the two-dimensional electron system in an n-type GaAs/AlGaAs heterostructure where delocalized states diverge in energy as B goes to zero indicating the presence of only localized states below the Fermi energy. The possible connection of this finding to the recently observed metal-insulator transition at B = 0 in the two-dimensional hole gas systems is discussed.

10 pages, 4 Postscript figures, To be published in Physical Review B (Rapid Communications) 58, Sept. 15, 1998

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• Levitation of quantum Hall critical states in a lattice model with spatially correlated disorder
• Metallic State of Low Mobility Silicon at High Carrier density induced by an Ionic Liquid
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• Mobility-Dependence of the Critical Density in Two-Dimensional Systems: An Empirical Relation
• Weakly chiral networks and 2D delocalized states in a weak magnetic field
• Global quantum Hall phase diagram from visibility diagrams
• Fate of the extended states in a vanishing magnetic field: the role of spins in strongly-interacting 2D electron systems