Soft magnetic underlayer with multilayer structure for perpendicular magnetic recording media

Multilayers with nonmagnetic interlayers for the soft magnetic underlayer were prepared in order to improve the soft magnetic properties and surface smoothness as well as reduce the domain configuration. The average size of surface grains decreased from 34 nm for a Ni-Fe single layer to 18 nm for [Ni--Fe/Si]/sub 5/ multilayer with increasing of number of Si interlayers. In the multilayer structure of [Fe--Co--B/Ni--Fe--O]/sub n/, the average surface roughness also decreased. [Ni-Fe/Si]/sub n/ and [Fe--Co--B/Ni--Fe--O]/sub n/ multilayers, which exhibited lower coercivity, H/sub c/, had no clear magnetic contrast.