AMORPHOUS CO-MO ALLOY-FILMS OBTAINED BY ALTERNATE-DEPOSITION

The Go-Mo system has a small negative heat of formation (Delta H-f = - 7 kJ/mol) and its composition favoring amorphization is limited in a r estricted region. In a multilayer scheme, an extra interfacial free en ergy stored in the films can extend the composition range for forming Go-Mo amorphous alloys. Multilayered films with totally 30 metal layer s were designed to have various overall compositions and prepared by a lternate-deposition at varying rates and switching times between two d epositions. It turned out that amorphous Go-Mo alloy films were indeed formed directly after deposition under appropriate conditions and the ir composition was in a relatively broadening region from 40 to 82 at% of Co. The calculated Gibbs free energy diagram gives a reasonable in terpretation of the observed amorphization as well as the compositiona l dependence of structural evolution of the formed amorphous Go-Mo all oys upon post-annealing. Besides, the changes of magnetic properties u pon post-annealing of the deposited films may also serve as an indirec t evidence of the observed structural evolution. The formation of amor phous Go-Mo alloys is attributed to an in-situ interfacial reaction dr iven by the interfacial free energy together with a utilization of the heats of condensation during vapor-to-solid transition.