The pinning properties of type-II superconductors can be efficientlycontrolled by using laterally nanostructured ferromagnet / superconductorbilayers. This will be illustrated by studying the flux pinning in thinsuperconducting Pb films which are deposited on top of two types of magneticnanostructures with out-of-plane magnetisation: (i) an array of dots, and (ii)an array of antidots, both made from a Co/Pt multilayer. The magnetisationcurves of the Pb film are extremely asymmetric with respect to the polarity ofthe magnetic field when the magnetic moments in the Co/Pt multilayer werealigned prior to measurement. This asymmetry proves that magnetic contributionsdominate the pinning potential that the magnetic nanostructures induce in thesuperconductor.
展开▼
