Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Patent
1994-11-16
1996-09-10
Resan, Stevan A.
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
428457, 428635, 428668, 428686, 428694MM, 428694EC, 428900, 369 13, 365122, 430945, G11B 1110, G11B 1304
Patent
active
055544363
ABSTRACT:
A magneto-optical recording medium is composed of first through fourth magnetic layers laminated in this order in such a way that an exchange coupling exists between any adjacent layers of the first through fourth magnetic layers so that a magnetization direction can be copied, wherein the first magnetic layer is a memory layer, the second magnetic layer is a writing layer, the third magnetic layer is a switching layer, and the fourth magnetic layer is an initializing layer. Further, respective Curie temperatures Tci satisfy an inequation Tc.sub.3 <Tc.sub.1 <Tc.sub.2, Tc.sub.4 (i=1, 2, 3, or 4 indicating an ordinal number of the magnetic layers); and the second magnetic layer exhibits an in-plane magnetization at room temperature, whereas, exhibits a perpendicular magnetization above a predetermined temperature set between the room temperature and Tc.sub.3 temperature. With this arrangement, after information is recorded on the memory layer based on the magnetization direction, the interface wall energy can be reduced, and the whole magnetic energy can be made substantially equivalent irrespective of the magnetization condition after recording. As a result, a stable recorded condition of the memory layer can be achieved.
REFERENCES:
patent: 5278810 (1994-01-01), Takahashi et al.
R. Malmhall et al. "Spin Directions in Exchange-Cpoupled Rare-Earth Transition Metal Double Layer Films with In-Plane Magnetic Intermediate Layer", Apr. 1992, Jpn.J.Appl. Phys. vol. 31, pp. 1050-1054.
T. Fukami et al. "Novel direct overwriting technology for magneto-optical disks by exchange-coupled RE-TM quadrilayered films", May 1, 1990, J.Appl.Phys, 67(9) pp. 4415-4416.
Y. Nakaki et al., "Overwrite Recording and Reading on Quadrilayer MO Disks Using an Optical Head with a Red-Light LD", Journal of The Magnetics Society of Japan, vol. 17, Supplement No. S1 (1993).
Iketani Naoyasu
Katayama Hiroyuki
Nakayama Junichiro
Ohta Kenji
Conlin David G.
Oliver Milton
Resan Stevan A.
Sharp Kabushiki Kaisha
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