Superconducting Vortex Pinning with Magnetic Dots: Does Size and Magnetic Configuration Matter?

The pinning of superconducting vortices in type-II superconductors has been studied for a long time due to the wide variety of unusual flux flow phenomena and more importantly, for its relevance in applications, since vortex pinning is one of the essential parameters controlling the enhancement of critical currents. A case of particular interest is the use of artificial magnetic pinning centers, since they can be fabricated to match well the characteristic length scales relevant for superconductivity and their magnetization offers another degree of freedom to influence the pinning properties. This article reviews our work on the role of the size and separation of the magnetic dots. Furthermore, we also show that the magnetic configuration can influence significantly the pinning strength, through the magnetic stray fields penetrating the superconductor, which can be drastically different.