Dresden 2003 – wissenschaftliches Programm
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SYQD: Quantum decoherence in solid state physics
SYQD 2: Quantum Decoherence in Solid State Physics II
SYQD 2.3: Vortrag
Dienstag, 25. März 2003, 18:00–18:15, HSZ/01
An experimental approach to investigate the influence of decoherence effects at surfaces on transport phenomena in tunnel junctions — •Detlef Diesing1, Walter Pfeiffer2, and Diana Vilchez3 — 1Institut für Schichten und Grenzflächen 3, Forschungszentrum Jülich — 2Institut für experimentelle Physik, Universität Würzburg — 3Brown University, Providence, Laboratory for Emerging Technology
One of the recurrent subjects in the study of quantum transport is the influence of dephasing processes on transfer rates. The dephasing or coherence loss of an electron can happen as well in the bulk as at the surface of a metal. Surface defects for example are known to influence the width of photoemission lines which can be discussed in terms of enhanced decoherence [1]. For studying the effect of quantum mechanical decoherence at metal surfaces on electron transport we have chosen as a model system thin film tunnel junctions consisting of Al and Ag electrodes whose thicknesses are in the range 15 nm - 20 nm. The thin metal films are separated by a 2 nm thick oxide layer. The tunnel current is found to increase when defect structures on the silver surface are produced by evaporation of submonolayer amounts of silver at T = 40 K. This effect is completely reversible, when the surface defects are annealed at T = 200 K. The current decrease due to the annealing effect of surface defects is compared to STM data of Schlößer et al.[2]. The current increase is discussed with its dependence on the energy of the tunneling electron and the structure of the defects. [1] F. Theilmann, R. Matzdorf, A. Goldmann, Surface Science 420 (1999) 33-42 [2] D.C. Schlößer et al., Surface Science 465 (2000) 19-39