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Exchange instability of the two-dimensional electron gas in semiconductor quantum wells

A. R. Goñi, U. Haboeck, C. Thomsen, K. Eberl, F. A. Reboredo, C. R. Proetto, and F. Guinea
Phys. Rev. B 65, 121313(R) – Published 13 March 2002
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Abstract

A two-dimensional (2D) electron gas formed in a modulation-doped GaAs/AlxGa1xAs single quantum well undergoes a first-order transition when the first excited subband is occupied with electrons, as the Fermi level is tuned into resonance with the excited subband by applying a dc voltage. Direct evidence for this effect is obtained from low-temperature photoluminescence spectra that display the sudden renormalization of the intersubband energy E01 upon the abrupt occupation of the first excited subband. Calculations within density-functional theory, which treat the 2D exchange potential exactly, show that this thermodynamical instability of the electron system is mainly driven by intersubband terms of the exchange Coulomb interaction, thus being a unique but fundamental property of an electron system with more than one occupied subband.

  • Received 10 January 2002

DOI:https://doi.org/10.1103/PhysRevB.65.121313

©2002 American Physical Society

Authors & Affiliations

A. R. Goñi1, U. Haboeck1, C. Thomsen1, K. Eberl2, F. A. Reboredo3, C. R. Proetto3, and F. Guinea4

  • 1Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
  • 2MPI für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
  • 3Comisión Nacional de Energía Atómica, Centro Atómico Bariloche, 8400 San Carlos de Bariloche, Argentina
  • 4Instituto de Ciencias de Materiales (CSIC), Cantoblanco, 28049 Madrid, Spain

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Vol. 65, Iss. 12 — 15 March 2002

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