Magnetic and Magneto-Optical Properties of Cobalt/nickel Multilayer Thin Films

Co/Ni multilayer thin films were prepared in a magnetron sputtering system, and their structural, magnetic and magneto-optical properties were experimentally investigated. It was found that the properties of Co/Ni multilayer thin films depend strongly on buffer layer materials and buffer layer crystalline orientation. Interface anisotropy is the main source for perpendicular magnetic anisotropy; and perpendicular magnetic anisotropy of Co/Ni multilayers can be achieved with Au buffer layers. The magnetic anisotropy constant depends on deposition rate as well as buffer layer texture. The Co/Ni multilayers on Au buffer layers show large Kerr rotation and magneto-optical figure of merit. The temperature response of the coercivity indicates that Co/Ni multilayers are more thermally stable than Co/Pd multilayers. The single crystal grain size is about 10 nm and the magnetic domain size is about 0.5 μm for the Co/Ni multilayers. The dominant coercivity mechanism is magnetic pinning, and ellipsometric analyses reveal that the pinning centers come from the interdiffussion of Co/Ni multilayers with the Au buffer layer.