Eur. Phys. J. B 40, 471-478 (2004)
https://doi.org/10.1140/epjb/e2004-00229-3

Vortex patterns and nucleation of superconductivity in mesoscopic rectangles and in hybrid superconductor/ferromagnet structures

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

Corresponding author: ^a mathieu.morelle@fys.kuleuven.ac.be

Received: 26 February 2004
Published online: 3 August 2004

Abstract

Nucleation of superconductivity and vortex patterns have been studied in mesoscopic samples providing the crossover between square and rectangular geometries. The measured nucleation line, , has been analyzed in the framework of the linearized Ginzburg-Landau theory. A very good agreement has been found between the theoretical boundary and the experimental data for rectangles with different aspect ratios. The superconductor/ferromagnet hybrids, such as magnetic Co/Pd dot in a superconducting loop and the dot on top of a superconducting disk have also been investigated. Pronounced effects of the dot on the boundary have been found, including strong asymmetry with respect to the field polarity.