Magneto-optical characteristics of double-layered amorphous RE-Fe films by rf sputtering

Abstract

Amorphous GdFe/TbFe double-layered films have been prepared by rf sputtering on glass substrates. GdFe films of about 300 A in thickness, TbFe films of about 500 A in thickness and SiOx films of about 900 A in thickness were successively deposited without breaking vacuum. The coercivity and polar Kerr rotation angle were measured as a function of rare-earth content. From these results, the optimum component of GdFe/TbFe double-layered films was determined. The coercivity of GdFe single-layered films and the GdFe layer in GdFe/TbFe double-layered films were also measured by polar Kerr hysteresis loops. It was found that the GdFe layer and the TbFe layer were exchange-coupled, since the coercivity of the GdFe layer in double-layered films was more than 10 times larger than that of GdFe single-layered films. Amorphous GdFe/TbFe double-layered media of the optimum component have been prepared on 200-mm-diam glass disks. A carrier-to-noise ratio (C/N) of 45 dB at 2.048 Mb/s (NRZ) was obtained, which is a few dB higher than that of TbFe single-layered films.