Magnetic properties of nickel nanostructures grown by nanosphere lithography technique

The self assembly nanosphere lithography (NSL) is an inexpensive scalable technique for production of Nanstrutures with controlled shape, size. The mono-dispersed 2D colloidal crystals (polystyrene nanoballs of 400nm size) on pre-treated Si (100) substrate is used as mask for creating nanofeatures of Ni. The monodisperse colloidal templates are prepared by drop coating method on hydrophilic Si (100) surfaces. The self assembled polystyrene nanoball templates are characterized by Scanning Electron Microscopy (SEM). Various defect structures, such as line defects, and point defects are observed in colloidal templates, which are inherent to self assembly process. The Ni-nanostructures (nanodots and nanowires) are obtained by growing ultra thin films (120 Å) of Ni onto the colloidal crystal template by vacuum thermal evaporation technique followed by mask removal. The nanostructures are characterized by scanning electron microscopy (SEM) for their structural features and by magnetic force microscopy (MFM) for magnetization properties. Random distribution of nanodot-size (ranging from 250-450 nm) and shapes are observed by scanning electron microscopy. Further we observed formation of nanorods of different dimensions and aligned in the plane of the substrate. Magnetic properties of these nanostructures formation magnetic nanorods are studied by magnetic force microscopy.