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TT: Fachverband Tiefe Temperaturen
TT 28: Transport - Poster Session
TT 28.1: Poster
Donnerstag, 29. März 2007, 14:00–17:45, Poster A
Conductance Measurements on Bismuth Nanobridges — •Hans-Fridtjof Pernau, Christian Schirm, and Elke Scheer — University of Konstanz, Department of Physics, 78457 Konstanz, Germany
By electron beam lithography and reactive ion etching we fabricate freestanding metallic bismuth nano-bridges which serve as starting point for arranging atomic-size and tunnel contacts with the help of the mechanically controlled breakjunction technique. Since the bridges are broken in cryogenic vacuum, the contacts are free of oxygen or other contamination. The transport measurements are performed in a 3He cryostat in the temperature range from 0.25 K up to 2 K and in transverse magnetic fields up to 8 T. After determining the preferred conductance values by recording conductance histograms, we study the conductance as a function of temperature, bias voltage and magnetic field at various contact values corresponding to those preferred conductance values. We observe reproducible conductance fluctuations as a function of both bias voltage and magnetic field and a well pronounced zero-bias anomaly which is modulated periodically with the magnetic field. We interprete our data in terms of phase coherent transport and onsetting superconductivity due to the granular structure of the film.