LARGE KERR ROTATION ANGLE AND MAGNETIC CHARACTERISTICS OF CO-CR/AL MULTILAYERS PREPARED BY PLASMA-FREE SPUTTERING

Multilayers of 50 - 1,500 angstrom Co-Cr/7 angstrom Al for perpendicular magnetic (PM) and magneto-optical (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 boundary on the plasma-free substrates. The reflectance R was as high as 70 % at the wave length-lambda in the range of 4,000 - 10,000 angstrom. The Kerr rotation angle theta(K) of the multilayer with the thickness of Co-Cr layer l(Co-Cr) of 150 angstrom was about 0.45 degrees at lambda of 4,000 angstrom. Also, theta(K) of 7 angstrom Al/1,500 angstrom Co-Cr/7 angstrom Al triple layers was as large as 0.41 degrees. The coercivity H(C) of the multilayers had value as high as about 1,000 Oe enough for PM media by post-annealing at a temperature as low as 150-degrees-C without significant decrease of R and theta(K). Consequently, the 150 angstrom Co-Cr/7 angstrom Al multilayers prepared by using the FTS apparatus may be very useful for the MO recording media as well as PM ones.