Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 7: Superconductivity & Solids At Low Temperature - Poster Session

TT 7.40: Poster

Montag, 27. März 2006, 14:00–17:45, P1

Diamagnetic screening properties of Nb/Ag and Nb/Ag/Fe layered structures — •C. Sürgers¹, H. Stalzer¹, A. Cosceev¹, and H. v. Löhneysen^1,2 — ¹Physikalisches Institut and DFG Center for Functional Nanostructures (CFN), Universität Karlsruhe, 76128 Karlsruhe, Germany — ²Forschungszentrum Karlsruhe, Institut für Festkörperphysik, 76021 Karlsruhe, Germany

The diamagnetic properties of Nb/Ag and Nb/Ag/Fe layered structures of various thicknesses are investigated by means of SQUID and vibrating sample magnetometry. Data were taken for different temperatures in magnetic fields slightly tilted from the orientation parallel to the surface. For Nb/Ag double layers, below the diamagnetic transition of the Nb layer a second transition caused by the proximity-induced screening currents in the Ag layer is observed. Furthermore, a peculiar position dependence of the Ag magnetization signal is likely to be due to the missing formation of Andreev bound states along the lateral extensions of the film. While for Ag layers thicker than the coherence length or penetration depth of Nb an additional Fe layer on top of Ag destroys the coherence of Andreev pairs, the diamagnetic signal of Ag is recovered if the Ag layer thickness is strongly reduced. This is interpreted as being due to the competition of proximity-induced superconductivity by Nb and pair breaking by Fe.