Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 28: Transport - Poster Session
TT 28.14: Poster
Donnerstag, 29. März 2007, 14:00–17:45, Poster A
Peculiarities of non-equilibrium conductance fluctuations — •Wanyin Cui1,2, Peter vom Stein1, Christoph Wallisser1, and Roland Schäfer1 — 1Forschungszentrum Karlsruhe, Institut für Festkörperphysik, Germany — 2Physikalisches Institut, Universität Karlsruhe, Germany
The quantum mechanical nature of conduction electrons leads to so-called universal conductance fluctuations in mesoscopic wires. We present new experimental results in the non-linear response regime at finite bias voltage. While earlier studies focused on the size of the fluctuation var(G) in the differential conductance, the present work takes a closer look at the critical magnetic field Bc (defined as the half width of the autocorrelation function) as well. A significant decrease of the fluctuation amplitude on a small voltage scale (Vdc ≤ 2VTh, Vdc and VTh refer to voltage drop and Thouless energy, respectively) for all investigeted samples is observed. It is accompanied by an increase of Bc for the majority of our samples. Both facts might point to a loss of phase coherence due to self-heating. However, for Vdc>2VTh an overall reduction of Bc is found indicating a further spreadout of the phase coherent region responsible for the fluctuations. The results are discussed with regard to recent theoretical work on non-equilibrium fluctuations.