Coexistence of a two- and three-dimensional Landau states in a wide parabolic quantum well

C. S. Sergio, G. M. Gusev, J. R. Leite, E. B. Olshanetskii, A. A. Bykov, N. T. Moshegov, A. K. Bakarov, A. I. Toropov, D. K. Maude, O. Estibals, and J. C. Portal
Phys. Rev. B 64, 115314 – Published 29 August 2001
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Abstract

Shubnikov–de Haas oscillations are measured in wide parabolic quantum wells with five to eight subbands in a tilted magnetic field. We find two types of oscillations. The oscillations at low magnetic fields are shifted toward higher field with the tilt angle increasing and can be attributed to two-dimensional Landau states. The position of the oscillations of the second type does not change with increasing the tilt angle which points to a three-dimensional character of these Landau states. We calculate the level broadening due to the elastic scattering rate Γ=ħ/2τ, where τ is the quantum time, and the energy separation between two-dimensional subbands, Δij=EjEi, in a parabolic well. For all levels we obtain ΓjΔij, which means that the levels overlap, supporting the observation of three-dimensional Landau states. Surprisingly, we find that the lowest subband, which has a smaller energy separation from the higher level, does not overlap with these subbands and forms a two-dimensional state.

  • Received 9 January 2001

DOI:https://doi.org/10.1103/PhysRevB.64.115314

©2001 American Physical Society

Authors & Affiliations

C. S. Sergio*, G. M. Gusev, and J. R. Leite

  • Instituto de Física da Universidade de São Paulo, SP, Brazil

E. B. Olshanetskii, A. A. Bykov, N. T. Moshegov, A. K. Bakarov, and A. I. Toropov

  • Institute of Semiconductor Physics, Novosibirsk, Russia

D. K. Maude and O. Estibals

  • GHMF, MPI-FKF/CNRS, BP-166, F-38042, Grenoble, Cedex 9, France
  • INSA-Toulouse, 31077, Cedex 4, France

J. C. Portal

  • GHMF, MPI-FKF/CNRS, BP-166, F-38042, Grenoble, Cedex 9, France,
  • INSA-Toulouse, 31077, Cedex 4, France,
  • Institut Universitaire de France, Toulouse, France

  • *Corresponding author. Electronic address: cassio@if.usp.br

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Issue

Vol. 64, Iss. 11 — 15 September 2001

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