Experimental and simulated properties of colloidally patterned cobalt thin films

Abstract

Patterned magnetic films have potential uses for magnetic data storage. We develop a method to quickly manufacture patterned magnetic films using spin coating of colloidal silica spheres followed by electrodeposition of ferromagnetic cobalt. These templates have been analyzed using scanning electron microscopy and magnetic force microscopy. They possess polycrystalline ordering of the spheres, with the orientation of the crystals radial to the center of spinning. Ferromagnetic cobalt filled the interstitials between the spheres. Model structures were numerically simulated using micromagnetic software. The results of these simulations revealed differences between patterned magnetic films and uniform films. In particular, the coercive field was greater in the patterned films. On the basis of micromagnetic theory and additional simulations, we propose mechanisms to explain these differences. These results matched those reported by others who have produced patterned magnetic films. The magnetic hysteresis behaviour of several representative samples was investigated experimentally at the University of Manitoba. The results from these samples partially confirmed the behaviour seen in the simulations; however, more measurements are needed to make firm conclusions.