Magnetic properties of Fe/Ti multilayered films for a magnetic recording medium

Films with combinations of Fe and Ti layers of various thicknesses (d/sub Fe/ of 10 approximately 1000 AA and d/sub Ti/ of 10 approximately 200 AA) have been prepared at Ar gas pressure of 2 mtorr in an apparatus with two pairs of facing-target sputtering sources. The total thickness of the Fe layers was fixed at 1000 AA for all specimen films. The saturation magnetization 4 pi M/sub s/ calculated from the expected total thickness of Fe layers decreased first gradually and then abruptly with d/sub Fe/, becoming almost zero at d/sub Fe/ of about 15 AA for all as-deposited films. The coercive force, H/sub c/, increased with decreasing d/sub Fe/, taking a maximum value of 270 Oe at d/sub Fe/ of 20 AA, and decreased abruptly with further decrease of d/sub Fe/. The films with modulation period of Fe(52 AA)/Ti(53 AA) which were annealed at temperatures above 200 degrees C had smaller 4 pi M than the as-deposited ones and H/sub c/ as high as 650 Oe at 230 approximately 325 degrees C. Films with this modulation period annealed at about 250 degrees C could be used as a magnetic recording medium because they have relatively large average 4 pi M/sub s/ of 4 kG, H/sub c/ of 650 Oe, moderate squareness of 0.7, and coercivity squareness of 0.8.<
>