Magnetic and structural properties of Co-Ni thin films prepared by oblique incidence deposition

Abstract

Thin films of cobalt, nickel, and their alloys have been produced on glass substrates by thermal evaporation at oblique angles of incidence α, measured with respect to the substrate normal, ranging from 20° to 78°. Resultant films are characterized by a columnar grain structure inclined toward the source by an angle β, also measured with respect to the substrate normal, such that 2 tan β∼tan α. For α>60°, the columnar grains assume a rodlike morphology surrounded by voids, whereas for α60°, the easy axis of magnetization is oriented in the vapor plane, defined by the plane parallel to both the direction of incident flux and substrate normal, whereas, for α60°, and parallel to the platelike morphology (and in the plane of the film), when α<60°. Finally, magnetic coercivity increases rapidly at the critical angle of 60°, as transition from platelike to rodlike morphology occurs.