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TT: Fachverband Tiefe Temperaturen

TT 28: Transport - Poster Session

TT 28.17: Poster

Thursday, March 29, 2007, 14:00–17:45, Poster A

Conductance fluctuations in inhomogeneous mesoscopic systems — •Alexander Kohler and Wolfgang Belzig — Universität Konstanz, D-78464 Konstanz, Germany

In mesoscopic systems the conductance is influenced by quantum interference effects, such as the weak localization correction and the universal conductance fluctuations. These conductance fluctuations have been observed in magnetic fields and are in some cases independent of sample size and impurity concentration. However, the magnetic field dependence is sensitive to the geometry of the wire and other inhomogeneities. Furthermore it is observed that conductance fluctuations in experiments change only slightly upon rearrangements of the disorder [1].

We investigate systems with a spatially inhomogeneous impurity concentration using standard diagrammatic methods. We find an oscillatory contribution (depending on the layer thickness) to the weak localization correction, reflecting the symmetry of the different diffusion modes in the wire. Complementary to the analysis of [2], we also study the influence of the motion of a single scatterer on the conductance fluctuations of a mesoscopic wire. Such effects can be probed by locally depleting a sample with an AFM.

[1] Elke Scheer, PhD thesis, Universität Karlsruhe, 1995.

[2] Feng, Lee, and Stone, Phys. Rev. Lett. 56, 1960 (1986).