Large Kerr rotation angle and magnetic characteristics of Co-Cr/Al multilayers prepared by plasma-free sputtering

Multilayers of 50 ~ 1500 Å Co-Cr/7 Å Al for perpendicular magnetic (PM) and magnetooptical (MO) recording media were prepared by the facing targets sputtering (FTS) method. It has been confirmed that the FTS apparatus can deposit the multilayers without significant interdiffusion at the boundary on the plasma-free substrates. The reflectance R was as high as 70% in the wavelength range of 4000 ~ 10,000 Å. The Kerr rotation angle θ_K of 7 Å Al/1500 Å Co-Cr/7 Å Al triple layers was as large as 0.41 °. The coercivity H_C of the multilayers was as high as about 1000 Oe, enough for PM media, by post-annealing at a temperature as low as 150°C without significant decrease of R and θ_K . Consequently, the 150 Å Co-Cr/7 Å Al multilayers prepared by using the FTS apparatus may be very useful for both MO and PM recording media