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 triangular array of submicron magnetic Au/Co/Au dots with in-plane magnetization. The rectangular dots can have two possible in-plane magnetic states: a single-domain state where the magnetization lies along the long axis of the dot and a multi-domain state. In this paper, we report on measurements of the field dependence of the critical current Ic(B) of the superconducting Pb film evaporated on top of this magnetic array. We observe a clear influence of the magnetic state of the dots on the pinning properties of the magnetic array, showing that there is an important pinning contribution due to the stray fields of the magnetic dots.