Microstructure and magnetic properties of BCC/FCC-mixed phase films prepared by sputtering from stainless steel targets

A new type of magnetic recording disk composed of a substrate and a recording layer both made from stainless steel has been proposed. The ferromagnetic and nonmagnetic stainless steel films needed for the recording layer and the underlayer, respectively, were deposited by sputtering the composite targets with SUS304 stainless steel plates and nickel chips as the first step in the preparation of these disks. Since films with a nickel content of 25-30 wt.% and FCC-phase crystal structure are nonmagnetic, they may be suitable as the underlayer to be deposited on the mechanically polished stainless steel substrates. On the other hand, since films with a nickel content of 15-20 wt.% and BCC/FCC-mixed-phase crystal structure have a high coercive force up to 200 Oe and a moderate saturation magnetization of 500 emu/cm³, they may be suitable for the recording layer