Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 32: Postersession Superconductivity: Josephson Junctions, SQUIDs, Heterostructures, Andreev Scattering, Vortex Physics, Cryodetectors, Measuring Devices, Cryotechnique

TT 32.13: Poster

Mittwoch, 25. März 2009, 14:00–18:00, P1A

The lateral S-(S/F)-S Josephson junctions — •Ondrej Vávra, Wolfgang Pfaff, and Christoph Strunk — Inst. for Exp. and Appl. Physics, Univ. Regensburg, Germany

Up to now the proximity effect at the superconductor-ferromagnet (S-F) interface was mainly demonstrated by the transport properties across the S-F interface [A.A. Golubov, M.Yu. Kupriyanov, and E. Ilichev, Rev. Mod. Phys. 76, 411 (2004).]. We present the results on lateral transport along the S-F interface and its utilization as a Josephson junction. We have prepared Nb based Josephson junctions which consist of Nb micro bridges with a Pd_0.95Fe_0.05 or Fe strip deposited perpendicular to the bridge. The width of the ferromagnetic strip was varied between 50 and 800 nm. The critical current (I_C) of the Nb-Pd_0.95Fe_0.05 and Nb-Fe bi-layer, respectively, is found to be significantly reduced by the proximity effect with the ferromagnet.

We have studied the temperature and magnetic field (B) dependencies of the critical current. In magnetic field an interference pattern I_C(B) is observed. In perpendicular magnetic field the junction exhibits I_C(B) dependence similar to a Fraunhofer pattern which proves the dc Josephson effect. We also investigate the dependence of I_C(B) oscillations on the orientation of the magnetic field. The control of the Josephson junction parameters is provided by third electrode connected to the F strip.