Fe-Co-B soft magnetic underlayer with radially oriented high anisotropy field for perpendicular magnetic recording disk

Fe-Co-B/Ni-Fe/Si films were prepared on Si wafers or glass disk substrates using a facing targets sputtering apparatus. Magnetic hysteresis characteristics show that the trilayers deposited on stationary glass disk exhibited higher coercivity and lower magnetic anisotropy field H_k comparing with that on Si wafer, and that films on rotating disk exhibited large H_k. X-ray diffraction studies reveal fcc (111) plane orientation in films on rotating disk and Si wafer, of which none was found in films on fixed disk. To conclude, it was found that the high H_k in Fe-Co-B films can be improved by increasing the deposition rate and the soft magnetic properties of Fe-Co-B/Ni-Fe/Si films, which deteriorate on glass substrates and improved by depositing them on rotating disks.