Bias effects on magnetic anisotropy of sputtered Co/Pt multilayers

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_s increases due to the well-defined interface, and the volume anisotropy energy K_v decreases owing to the in-plane compressive strain in Co layers having negative magnetostriction constant. In Pt bias films, the anisotropy K_u increases by the enhancement in K_s, which arises from the in-plane compressive strain in CoPt alloyed layers formed at the interfaces