DOI: 10.1209/epl/i2001-00561-8


Europhys. Lett., 56 (4) , pp. 590-595 (2001)

Inverse proximity effect in superconductors near ferromagnetic material

M. A. Sillanpää¹, T. T. Heikkilä^{2, 3}, R. K. Lindell¹ and P. J. Hakonen<sup>1

1</sup>  Low Temperature Laboratory, Helsinki University of Technology P.O.Box 2200, FIN-02015 HUT, Finland
²  Materials Physics Laboratory, Helsinki University of Technology P.O.Box 2200, FIN-02015 HUT, Finland
³  Institut für Theoretische Festkörperphysik, Universität Karlsruhe D-76128 Karlsruhe, Germany

Mika.Sillanpaa@iki.fi

(Received 20 April 2001; accepted in final form 27 August 2001)

Abstract
We study the electronic density of states in a mesoscopic superconductor near a transparent interface with a ferromagnetic metal. In our tunnel spectroscopy experiment, a substantial density of states is observed at sub-gap energies close to a ferromagnet. We compare our data with detailed calculations based on the Usadel equation, where the effect of the ferromagnet is treated as an effective boundary condition. We achieve an excellent agreement with theory when non-ideal quality of the interface is taken into account.

PACS
74.50.+r - Proximity effects, weak links, tunneling phenomena, and Josephson effects.


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