Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 25: Correlated Electrons - Poster Session
TT 25.64: Poster
Mittwoch, 29. März 2006, 14:30–18:30, P1
Detection of percolation-depercolation phase transition in silver rich AgxSe thin films by magneto transport measurements — •Marc von Kreutzbruck1, Kai Allweins1, Gertrud Lembke1, Boris Mogwitz2, Carsten Korte2, and Jürgen Janek2 — 1Institut für Angewandte Physik, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 16, D-35392 Gießen, Germany — 2Physikalisch-Chemisches Institut, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 58, D-35392 Gießen, Germany
In this work we investigate the galvanomagnetic transport properties of polycrystalline AgxSe thin films with a thickness ranging from 6 nm to 200 nm and a silver excess of about x = 2.3. The latter is near the percolation-depercolation phase transition, where the transport is mainly mediated by silver paths and silver clusters on the nanoscale. Sample characterization by measuring the conductivity, Kohler Slope, and temperature behavior yielded no clear indication whether a sample is in the percolative regime. A more reliable characterization of the semiconductor/metal heterostructure was obtained by measuring weak localization effects. The determination of the corresponding characteristic scattering lengths, such as the spin-orbit length Lso and the inelastic length Li(T), divided the AgxSe films clearly into two groups. We interpret these findings as an indication that the weak localization approach can be used as a sound method to determine the percolative nature of a 2D- heterostructure. An analytical model with predictive power is proposed.