| 摘要 |
PURPOSE:To obtain a stable electromagnetic conversion characteristic by passing repeatedly a magnetic recording medium through the inside of a magnetic field wherein a magnetic field in a different direction is generated and the magnetic field intensity has a space ditribution and subjecting the same to a cooling treatment in the magnetic field from a specific temp. or above to around a room temp. CONSTITUTION:Fe3O4 contg. Co and Cu respectivly at 4wt% in the entire metallic element is used as a target, and a thin film of Fe3O3 having about 3,000Angstrom thickness and contg. Co and Cu is formed on a heat resistant high polymer film substrate by sputtering at 600W sputtering power and 8X10<-3>Torr sputtering pressure in gaseous argon. The film is oxidized for one hour at 260 deg.C whereby a thin film of iron oxide consisting essentially of the intermediate compsn. of Fe3O4-gamma-Fe2O3 is obtd. A floppy disc 6 cut from such thin film is once heated to 200 deg.C and is passed through the space between magnets 2 and 3 and is slowly cooled to 50 deg.C at 10 deg.C/min speed while the disc is rotated at 6rpm rotating speed. The high effect of an improvement in a magnetic characteristic and a reduction in a demagnetization characteristic under pressure by half is thus obtd. |
