Influence of Ni content on the microstructure and magnetic and magneto-optical properties of sputtered (Co1-xNix)Pt3 alloy films

Influence of Ni content on the microstructure and magnetic and magneto-optical (MO) properties of sputtered (Co1-xNix)Pt3 alloy films has been investigated by means of Kerr spectrometer, Kerr hysteresis looper, X-ray diffractometer (XRD), and atomic force microscopy (AFM). On the whole, the addition of Ni to the CoPt3 alloy film simultaneously decreases the Curie temperature TC and the Kerr rotation angle θK, but the decrease of TC with Ni content is more visible. When the Ni content x is increased from 0 to 0.33, TC decreases from 273 ○C to 233 ○C, whereas the decrease of θK is quite limited and the film still preserves a strong perpendicular magnetic anisotropy (PMA) and a high coercivity, indicating that the (Co1-xNix)Pt3 alloy film with x=0.33 can be used for practical MO applications. Further increase of Ni content decreases the θK significantly and destroys the PMA. XRD and AFM studies show that adding a small amount of Ni in the CoPt3 alloy film will promote the growth of grains and roughen the film surface, and thus enhance the coercivity of the film. We observe also that both the coercivity and PMA are not sensitive to the (111) preferred orientation of the (Co1-xNix )Pt3 alloy films.