Sphere surface-induced exchange bias effect of NiO/FeNi nanostructures

We demonstrated the fabrication of the ordered exchange-biased bilayer NiO/FeNi on the curved surface substrate. The curved substrate, consisting of compact polystyrene colloid sphere arrays, was grown on Si wafer by self-assembly technology. The size and space of the biased-dots were estimated based on the film thickness variation induced by the sphere surfaces. The bias field H E of the biased-dots increased with decreasing size of the colloid sphere. Compared to the continuous flat film deposited on the silicon substrate, the biased-dots on sphere exhibited much larger H E and the blocking temperature T B decreased.