Static Tests Of TbFe Films For Magneto-Optical Recordings

Abstract
A number of TbFe thin films on 2"x2" glass slides were evaluated as candidates for an erasable memory. Maximum bit density is better then 1μm center to center, limited by the resolving power of the optics. The homogeneity of the films is very good, at least on a microscopic level. The required incident power in 25 ns pulses for writing a 50% bit is in several cases below 5 mW. A variation of a factor of 2 in write power can be tolerated without an appreciable loss in either resolution or error rate. An externally applied biasing field, H, equal to one quarter of the value of coercivity, Hc, is adequate both for writing and for erasing a bit. As fields of the order of 0.6 Hc did not affect the signal, it appears that the tolerance of the system to variations in H is high. From the limited number of samples that have been measured, one can only make educated guesses about optimum values of these parameters. It seems that the maximum in performance lies somewhere in the 100-1000 A and 800-3500 Oe range. However the maximum is very broad, so that probably anything in this range should be adequate.