Arrays of nanoscaled single and multi domain magnetic dots: their effect in magnetic properties of superconducting Nb thin films

V. BEKERIS1, C. CHILOTTE1, D. PÉREZ DAROCA1, G. PASQUINI1, C.-P LI, F. CASANOVA, J. VILLEGAS AND I. SCHULLER

Side, Turquía

Conferencia; International Conference in Superconductivity and Magnetism; 2008

     We explore both the normal and superconducting magnetic response of Nb thin films (~100 nm thick), deposited on triangular arrays of magnetic (Co, Fe) nanodots. Dots (~ 90 nm in diameter) were grown on self-assembled SiO2 porous substrates [1], with a mean distance of ~120 nm. Cobalt dots are single domain with in plane magnetization; Fe dots are thicker and are in magnetic vortex state configuration with stronger perpendicular stray field component. Ac susceptibility and dc magnetization show different behavior according to the magnetic state of dots.  Although their magnetization is reversed in the studied field interval (low coercive fields), the initial magnetic sate of Fe dots is relevant in the dc magnetization loops M(H) of the superconducting samples. Enhanced pinning at matching fields is reported, in dc and ac measurements. The effect of superconductivity on the magnetic properties of the particles is also discussed. [1] Chang-Peng Li et.al., J. Appl. Phys. 100, 074318 (2006).