Dresden 2009 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 26: Poster II

DY 26.10: Poster

Donnerstag, 26. März 2009, 16:00–18:00, P1A

Conductivity in continuous systems with disordered potential — •Steffen Röthel and Rudolf Friedrich — Westfälische Wilhelms-Universtät Münster, Institut for Theoretical Physics, Wilhelm-Klemm-Str. 9, 48149 Münster

We consider the behavior of an overdamped charged particle moving in a disordered potential in the presence of an external electric field under the influence of a Gaussian white noise. Applying periodic boundary conditions for the disordered potential a Fokker-Planck treatment of the corresponding Langevin equation allows to determine the current density. For weak disorder the case of an oscillating sinusoidal electric field leads to higher harmonic contribution to the current density. We present the frequency spectrum of the conductivity for the first two harmonics for various statistical properties of the disordered potential in one dimension. Furthermore, we calculate the conductivity in a two-dimensional disordered potential in the case of a stationary electric field for various temperatures. The experimental determination of the current-voltage relation and in particular the frequency dependence of the current can be used to identify properties of the disordered potential, and, in turn, to characterize the spatial structure of the material probe.