Rights statement: © 1997 The American Physical Society
Final published version, 125 KB, PDF document
Research output: Contribution to Journal/Magazine › Journal article › peer-review
| <mark>Journal publication date</mark> | 15/10/1997 |
|---|---|
| <mark>Journal</mark> | Physical review B |
| Issue number | 16 |
| Volume | 56 |
| Number of pages | 7 |
| Pages (from-to) | 10446-10452 |
| Publication Status | Published |
| <mark>Original language</mark> | English |
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.