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Quantum versus semiclassical analysis of the conductivity of two-dimensional electrons in a magnetic field

Research output: Contribution to journalJournal article

Published

  • M Hayne
  • Alan Usher
  • Jeffery J Harris
  • C Tom Foxon
Journal publication date15/10/1997
JournalPhysical Review B
Journal number16
Volume56
Number of pages7
Pages10446-10452
Original languageEnglish

Abstract

We present experimental evidence for the levitation of extended slates of a two-dimensional electron system in a magnetic field, and establish the presence of alternating regions of localized and extended states in the density of states to Landau-level filling factors (nu) as high as 80. Monitoring the Hall voltage of a modulation-doped GaAs/AlxGa1-xAs heterojunction at fixed magnetic field during continuous illumination from light-emitting diodes reveals a steplike structure with plateaus at even integer nu between 22 and 80 at a temperature of 0.3 K. We derive a general expression for the conductivity due to rectangular bands of extended states, and show that the observed temperature dependence of the Shubnikov-de Haas oscillations is consistent with this picture. An analysis of the oscillations using this expression reveals the predicted levitation of the extended states.

Bibliographic note

© 1997 The American Physical Society