Most magnetic devices marketed nowadays still use bulk or thin film materials, this is soon to change with the advent of nano-fabrication technologies [1]. Proper scaling requires that the magnetic particle size decreases with the scaling factor at the same rate as all of the other dimensions. This is necessary in order to keep the number of particles in a bit cell constant (at a few hundred per cell) [2]. Magnetic nano-structures represents future miniaturization in magnetic recording devices, and detailed understanding of the formation of magnetic vortices in closely spaced ferromagnetic nanoparticles is important for the design of ultra-high-density magnetic devices. It is necessary to achieve ultra-high density in magnetic storage media so that the lateral size of the information bits be as small as possible, without the bit volume reaching the superparamagnetic limit beyond which the energy needed to switch the magnetization of a bit becomes less than the thermal energy, and nano-fabrication offers the technical ability to fabricate magnetic objects with nano scale precision having unique magnetic properties, which may be tailored by manipulating the size, the shape, or the composition of the nanostructures [3]. The magnetic nano-structures of have been formed by different rates of heavy ion irradiation of thin films. The fluence affects both anisotropy and spontaneous magnetization.