Europhys. Lett.
Volume 76, Number 1, October 2006
Page(s) 121 - 127
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 30 August 2006
Europhys. Lett., 76 (1), pp. 121-127 (2006)
DOI: 10.1209/epl/i2006-10233-3

Field-screening properties of proximity-coupled $\chem{Nb/Ag}$ double layers

H. Stalzer1, A. Cosceev1, C. Sürgers1 and H. v. Löhneysen1, 2

1  Physikalisches Institut and Center for Functional Nanostructures Universität Karlsruhe - D-76128 Karlsruhe, Germany
2  Forschungszentrum Karlsruhe, Institut für Festkörperphysik D-76021 Karlsruhe, Germany

received 20 June 2006; accepted 7 August 2006
published online 30 August 2006

In Nb/Ag layers, the induced superconductivity in Ag by Nb gives rise to diamagnetic screening currents in the Ag layer well below the transition temperature of the superconductor. By investigating the position dependence of the individual diamagnetic transitions of Nb and Ag with a gradiometer in a nearly parallel magnetic field, we find that the screening of the Ag layer is remarkably different compared to the Nb layer. While for the Nb layer a strong out-of-plane contribution is observed due to the large demagnetization factor, such a contribution is absent for the Ag layer. This can be explained by the partial overscreening of the magnetic field, i.e. a reduced diamagnetic response of the Ag layer, as suggested by the theory for the clean limit.

74.25.Ha - Magnetic properties.
74.45.+c - Proximity effects; Andreev effect; SN and SNS junctions.
74.78.-w - Superconducting films and low-dimensional structures.

© EDP Sciences 2006