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 32.16: Poster
Mittwoch, 25. März 2009, 14:00–18:00, P1A
Crossover from 2D-3D behaviour in superconducting Nb/CuNi bilayers in a magnetic field — •Jan-Michael Kehrle2, Vladimir Zdravkov1,2, Günter Obermeier2, Roman Morari1, Eugen Antropov1, Andrei Prepelitsa1, Claus Müller2, Achim Wixforth2, Siegfried Horn2, Reinhard Tidecks2, and Anatolie Sidorenko1,2,3 — 1Institute of Electronic Engineering and Industrial Technologies ASM, Kishinev, MD2028, Moldova — 2Institut für Physik, Universität Augsburg, D-86159 Augsburg, Germany — 3Institute of Nanotechnology (INT), Forschungszentrum Karlsruhe, D-76021 Karlsruhe, Germany
A dimensional crossover in an external magnetic field, applied parallel to the layers, has been found for superconductor/ferromagnet (S/F) bilayers of Nb/CuNi. For decreasing temperature the square-root 2D-behaviour of the upper critical magnetic field, Bc2||(T) on the temperature, in the vicinity of the critical temperature Tc switches to the linear 3D-behaviour below the crossover temperature, Tcr. The 2D-3D crossover also occurs concerning the temperature dependence of superconducting fluctuations in the critical fluctuation regime. The fluctuation conductivity exhibits a 2D-behaviour in zero- and weak magnetic fields close to Tc, switching to a 3D-behaviour in strong magnetic fields at low temperatures. In a S/F bilayer the quasi-one dimensional Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) like state is realized, so that the superconducting properties are governed by interference effects of the pairing wave functions, i.e. by the pairing function flux through the S/F interface.