Crystal structures and magnetic properties of Fe/Cu multilayer films

Fe single layer films and Fe/Cu multilayer films were prepared by an rf-sputtering method, and the relationships between the crystal structures and magnetic properties were investigated. Fe single layer films with saturation magnetic flux density Bs=2.1(T), comparable to bulk Fe, were obtained under sputtering conditions of high rf power and low Ar gas pressure. The crystal structures of multilayer films were found to depend on the thickness of the individual Fe layers, dFe, and Cu layers, dCu. Fcc single phase crystal structure was obtained for dFe=1.7nm, dCu=4.9 ∼ 9.8nm. At other combinations of dFeand dCu, the crystal. structures were mixtures of fcc and bcc. Coercive forces of the fcc single phase films were larger than those of the films with a mixture of fcc and bcc. When the films were mixed fcc and bcc, Bswas about 2.0(T) for thicknesses dFe=4.2 ∼ 8.4nm, and in thinner films, Bsdecreased with decreasing dFe. Bsof fcc single -phase films phase was sharply decreased as film thickness decreased.