Europhys. Lett.
Volume 65, Number 4, February 2004
Page(s) 546 - 552
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 February 2004
Europhys. Lett., 65 (4) , pp. 546-552 (2004)
DOI: 10.1209/epl/i2003-10121-4

Influence of the stray field of a magnetic dot on the nucleation of superconductivity in a disk

D. S. Golubovic, W. V. Pogosov, M. Morelle and V. V. Moshchalkov

Nanoscale Superconductivity and Magnetism Group Laboratory for Solid State Physics and Magnetism, K. U. Leuven Celestijnenlaan 200 D, B-3001 Leuven, Belgium

(Received 17 September 2003; accepted in final form 10 December 2003)

We have investigated the nucleation of superconductivity in an $\chem{Al}$ mesoscopic disk, with a magnetic dot on the top. The dot is magnetized perpendicularly, and its magnetic field is inhomogeneous. The $\chem{Al}$ disk and magnetic dot are separated by an insulating layer, which ensures that there is only magnetic interaction between them. This hybrid superconductor/ferromagnet structure exhibits the maximum critical temperature for a finite value of the perpendicular applied magnetic field, which is parallel to the magnetization of magnetic dot. We have found a good agreement between the experimental data for the superconductor/normal metal phase boundary and the theoretical predictions based on the Ginzburg-Landau theory.

74.78.Na - Mesoscopic and nanoscale systems.
74.25.Dw - Superconductivity phase diagrams.

© EDP Sciences 2004