Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 8: Superconductivity - Poster Session
TT 8.29: Poster
Montag, 26. März 2007, 14:00–17:45, Poster A
A quest for the optimal design of π-coupled Josephson junctions — •Dirk Sprungmann, Kurt Westerholt, and Hartmut Zabel — Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum
In recent years investigations of so called π-coupled Josephson junctions
became very popular. In an ordinary currentless SIS or SNS junction the pair wave functions on both sides of
the tunnel barrier have a phase shift of zero. By introducing a thin ferromagnetic layer with a certain thickness dFc
between the two superconductors it is possible, to obtain a phase shift of π between the two superconducting layers in the
ground state. This
causes a sign change of the critical Josephson current Ic and leads to a crossover within the Ic(dF)-curve.
To establish a solid basis to analyse these electronic components systematically, we first tried to find an optimal design of the
junction. In order to avoid any breaking of the vacuum and to keep all the interfaces in the junction clean, we checked two
in-situ preparation procedures, in which only shadow masks and dry-etching processes are applied. We will compare these in-situ
designs with established concepts using e-beam lithography.
We present abortive and successfull sample designs of these exciting electronic devices and describe advantages disadvantages as
well as crucial pitfalls.
We acknowledge financial support through SFB 491.