NEW HIGH-PERFORMANCE MAGNETOOPTIC MEDIA - TB BI/FECO AND TB/PB/FECO SUPERLATTICES/

Tb/Bi/FeCo and Tb/Pb/FeCo superlattices are demonstrated to offer Ken rotation and figure of merit (reflectivity times Ken rotation) substan tially exceeding that offered by conventional TbFeCo recording materia ls, particularly at blue wavelengths. Superlattices such as 4.4 Angstr om Tb/2.0 Angstrom Bi/5.0 Angstrom Fe0.6Co0.4 exhibit squarenesses sui table for magneto-optical recording and figure of merits of 0.20, 0.18 , and 0.14 at wavelengths of 780, 650, and 430 nm, respectively. Dynam ic testing with 780 and 490 nm light demonstrates that the high figure s of merit translate to carriers several dB above those produced by Tb FeCo alloys. Furthermore, very high carrier-to-noise ratios such as 54 dB at a mark length of 0.75 mu m (4 MHz) and 60 dB at long mark lengt hs (1 MHz) are obtained using 490 nm light and a bandwidth of 30 kHz. (C) 1997 American Institute of Physics.