Co/Pt multilayers have been sputter-deposited with negative substrate bias voltage applied during deposition of Co or Pt layers. In the Co bias films, the surface anisotropy energy K/sub s/ increases due to the well-defined interface, and the volume anisotropy energy K/sub v/ decreases owing to the in-plane compressive strain in Co layers having negative magnetostriction constant. In Pt bias films, the anisotropy K/sub u/ increases by the enhancement in K/sub s/, which arises from the in-plane compressive strain in CoPt alloyed layers formed at the interfaces.ETX