The application of shadow nanosphere lithography for the preparation of large-area, two-dimensional, metallic nanostructures of different shape is described. Through changing the mask morphology by temperature processing and varying the evaporation conditions, particles with morphologies such as rings, rods, and dots have been produced. This process allows outstanding control of the size and morphology of the particles. The efficient technique is shown to scale down the size of metallic nanoparticles from 200 to 30 nm, while preserving the original nanosphere spacing and order. The 150-nm-diameter Fe rings produced by this method show ferromagnetic behavior, which was predicted by theoretical simulation. All the experimental results were confirmed by computer simulations, which also showed the possibility of creating periodic arrays of any other geometrical shape.

Exchange bias effects have been observed in an array of submicron antiferromagnetic-ferromagnetic dots prepared by nanosphere lithography. The angular dependences of the exchange bias field HE, coercivity HC, and squareness ratio MR/MS of the array of dots have been measured and compared with those of a continuous film prepared under the same conditions. An HE enhancement of around 30% is observed along the field-cooling direction in the dots. The possible mechanisms responsible for this enhancement are discussed. Moreover, magnetic imaging reveals that complex magnetization reversal mechanisms occur in the nanostructures, which cause significant differences in the shape of the hysteresis loops, when compared to the exchange biased continuous films.