The effects of underlayer NiFeX on the magnetic properties of CoPt films

The effects of soft magnetic underlayer, NiFeX, on the magnetic properties of CoPt films has been studied as a function of substrate bias and Ar pressure during the NiFeX deposition and sputter etch time prior to the CoPt film deposition. It is concluded that the FCC (111) texture of NiFeX plays a dominant role in the c-axis orientation of CoPt films, Applying substrate bias or using P-Ta as an underlayer, the FCC (111) texture of NiFeX films can be greatly enhanced. Applying no substrate bias and sputtering at high Ar pressure, the FCC (111) texture of NiPeX films can be suppressed. As a consequence, the anisotropy of the CoPt films can be made either in-plane or perpendicular depending on the crystallinity of the NiPeX films. It is also found that a strong ferromagnetic exchange field between NiPeX and CoPt films favors the growth of CoPt films with c-axis in-plane, with a typical symptom of high in-plane moment thickness product and low remnant coercivity.