Soft disorder effects in the conductance quantization in quantum point contacts: Indirect backscattering statistics

S. N. Rashkeev, A. M. Zagoskin, R. I. Shekhter, G. Wendin

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The breakdown of conductance quantization in a quantum point contact in the presence of random long-range impurity potential is discussed. It is shown that in the linear response regime a decisive role is played by the indirect backscattering mechanism via quasilocalized states at the Fermi level; this can provide a much higher backscattering rate than any direct backscattering process. For realistic contact lengths (≤ 2000 nm) the scattering processes prove to be independent, in spite of coherence of the electron wave. The distribution function of conductance fluctuations is obtained by direct numerical calculations as well as estimated within an analytical model. It is shown to be a generalized Poisson distribution. The quantum point contact performance is estimated for different choices of parameters. In particular, the larger the intermode distance in comparison with the amplitude of the random impurity potential, the better is the performance.

Original languageEnglish
Pages (from-to)279-283
Number of pages5
JournalSolid State Communications
Issue number4
Publication statusPublished - Jan 1996



  • A. disordered systems
  • A. nanostructures
  • D. electronic transport
  • D. localized electronic states

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry

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