Magnetic and crystallographic properties of Cohyphen;W films, deposited in an alternating multilayer structure by a magnetron dchyphen;sputtering method, have been investigated as a function of CO composition and Co layer thickness. Regular periodic stacking without interdiffusion of Co and W atoms is made on all films with various periodicities (5ndash;100 Aring;) and thickness ratios (8/1ndash;1/4). Films with small periodicities (less than 30 Aring;) composed of large thickness ratios have an artificial superlattice structure with crystallographic coherence between Co and W layers, where they grow epitaxially on the closest planes.1The crystallographic structures of films are hcp with the (001) plane parallel to the film for films with a Co layer thicker than the W layer, and bcc with the (110) plane parallel to the film for films with a Co layer thinner than the W layer. Films with small periodicities composed of small thickness ratios have an artificial superstructure with periodic stacking of constituent layers of an amorphous phase. Films with large periodicities have an artificial superstructure wih periodic stacking of constituent layers of a crystalline phase. Films are ferromagnetic with an easy magnetization direction in the film plane. The magnetization of Co in Cohyphen;W films is smaller than that of bulk Co. The paramagnetism or ferromagnetism of films with an extremely small magnetization are observed in films with small periodicities, especially composed of a Co layer thinner than the W layer. The small magnetization of Co is attributed to decreases in both the magnetization and the Curie temperature of Co due to lattice deformation. Films with a bcc structure exhibit a Curie temperature of about 600 K. The magnetization of Co in films with a bcc structure seems to be larger than that in films with a hcp structure.
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