Oblon, Spivak, McClelland, Maier & Neustadt
Magnetic recording medium comprising a magnetic layer containing a specified magnetic ferrite powder and having a curie temperature up to 180.degree. C.
 According to the invention, a magnetic recording medium is formed by using magnetic powder having a composition of the following formula: EQU MeO.multidot.n[Fe.sub.2-x-y-z Ga.sub.x Cr.sub.y Al.sub.z O.sub.3 ] wherein Me is at least on element selected from the group consisting of Ba, Sr, Pb, and Ca, EQU 4.5.ltoreq.n.ltoreq.6, x.gtoreq.0, y.gtoreq.0, z.gtoreq.0, EQU x/3+y/4+z/6.gtoreq.1/6, and EQU x/6+y/10+z/11.ltoreq.1/6, preferably the number of those particles having a particle size of from 0.5d to 1.5d being at least 65% of the entire particles wherein is an average particle size, and the Fe content on the particle surface being substantially equal to the Fe content in the particle interior, and blending the powder with a binder. Thermomagnetic recording and thermomagnetic duplication are carried out using the medium. There results a magnetic layer which has high Hc, is not easily erased once recorded, has high squareness ratio, and enables thermomagnetic recording and thermomagnetic duplication at 100.degree. to 180.degree. C. with outputs having an excellent frequency response and minimized variation and noise. 
TDK Corporation
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Tetsuhito Hideharu Osamu Haruyuki Shohei Atsushi Shigeo
Yoneyama Moro Kohmoto Takahashi Mimura Makimura Satoh