Nonequilibrium mesoscopic conductance fluctuations

T. Ludwig, Ya. M. Blanter, and A. D. Mirlin
Phys. Rev. B 70, 235315 – Published 13 December 2004

Abstract

We investigate the amplitude of mesoscopic fluctuations of the differential conductance of a metallic wire at arbitrary bias voltage V. For noninteracting electrons, the variance δg2 increases with V. The asymptotic large-V behavior is δg2VVc (where eVc=DL2 is the Thouless energy), in agreement with the earlier prediction by Larkin and Khmelnitskii. We find, however, that this asymptotics has a very small numerical prefactor and sets in at very large VVc only, which strongly complicates its experimental observation. This high-voltage behavior is preceded by a crossover regime, VVc30, where the conductance variance increases by a factor 3 as compared to its value in the regime of universal conductance fluctuations (i.e., at V0). We further analyze the effect of dephasing due to the electron-electron scattering on δg2 at high voltages. With the Coulomb interaction taken into account, the amplitude of conductance fluctuations becomes a nonmonotonic function of V. Specifically, δg2 drops as 1V for voltages VgVc, where g is the dimensionless conductance. In this regime, the conductance fluctuations are dominated by quantum-coherent regions of the wire adjacent to the reservoirs.

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  • Received 2 June 2004

DOI:https://doi.org/10.1103/PhysRevB.70.235315

©2004 American Physical Society

Authors & Affiliations

T. Ludwig1, Ya. M. Blanter2, and A. D. Mirlin1,3,*

  • 1Institut für Nanotechnologie, Forschungszentrum Karlsruhe, 76021 Karlsruhe, Germany
  • 2Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
  • 3Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, 76128 Karlsruhe, Germany

  • *Also at Petersburg Nuclear Physics Institute, 188350 St. Petersburg, Russia.

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Issue

Vol. 70, Iss. 23 — 15 December 2004

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