Flux pinning in a superconducting film by a regular array of magnetic dots

We have studied flux pinning in thin superconducting Pb films covering a tr iangular array of submicron magnetic Au/Co/Au dots with in-plane magnetizat ion. The rectangular dots can have two possible in-plane magnetic slates: a single-domain state where the magnetization lies parallel to the long axis of the dot and a multi-domain state. In this paper, we report on the measu rements of the field dependence of the critical current I-c(B) of a superco nducting Pb film evaporated on top of this magnetic array. We observe a cle ar influence of the magnetic state of the dots on the pinning properties of the magnetic array, showing that there is an important pinning contributio n due to the stray fields of the magnetic dots. (C) 2000 Elsevier Science B .V. All rights reserved.