Large-area patterned magnetic nanostructures by self-assembling of polystyrene nanospheres

Abstract

ABSTRACTIn this work, dot and anti-dot structures in Co, Ni, Ni80Fe20, Fe50Pd50, Fe73.5Cu1Nb3Si13.5B9 and Fe78B13Si9 thin films have been produced by means of nanosphere lithography. Two multi-step processes have been followed and will be here described. The first one directly exploits polystyrene nanosheres (PN) as a mask to fabricate arrays of magnetic nanoholes and dots. In the second case, the nanospheres are used to design a polymeric mask of a photoresist subsequently used to pattern a magnetic nanostructure on a film. Advantages and disadvantages of the two lithographical techniques will be here highlighted. In both processes, the dimension and mutual distance of the patterns are dependent on the starting PN diameter (in the interval 500-800 nm). Samples microstructure has been studied by means of SEM and AFM microscopy. Room-temperature hysteresis loops have been measured by an AGFM (Alternating Gradient Field Magnetometer). MFM microscopy has been exploited to study the magnetic domain pattern. All produced systems have been observed to display tunable microstructure and, consequently, various magnetic properties for application.