Magnetic recording medium comprising protrusion on its surface and a plasma treated substrate and recording/reproducing method therefor
AssigneeTDK Corporation
InventorsMasatoshi Nakayama, Kunihiro Ueda, Yuichi Kubota
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Abstract
A magnetic recording medium comprising a ferromagnetic metal thin film layer formed on one surface of a flexible non-magnetic substrate and primarily comprising cobalt and oxygen is improved in durability by treating the substrate with a plasma at a frequency of 10 kHz to 200 kHz, and providing the magnetic layer on the surface with protrusions having a height of 30 to 300 .ANG. at an average density of at least 10.sup.5 /a.sup.2 per square millimeter of the surface, provided that the magnetic recording medium is passed for recording/reproducing operation across a magnetic head with a gap having a distance a as expressed n .mu.m.
Claims11
A magnetic recording medium comprising
- a flexible substrate having opposed major surfaces, and
- a ferromagnetic metal thin film layer on one surface of the substrate primarily comprisnig cobalt, the magnetic recording medium being used in combination with a magnetic head having a gap, characterized in that
- said substrate is plasma treated at a frequency of 10 KHz to 200 KHz,
- said metal thin film layer contains oxygen, and
- the medium has protrusions on its surface at an average density of at least 10.sup.5 /a.sup.2 per square millimeter of the surface, the protrusions having a height of 30 to 300 .ANG., where a is the distance of the magnetic head gap and is 0.1 to 0.5 .mu.m.
A method for conducting recording/reproducing operation on a magnetic recording medium comprising a flexible substrate having opposed major surfaces, and a ferromagnetic metal thin film layer on one surface of the substrate principally comprising cobalt, by passing the medium across a magnetic head having a gap, characterized in that
- said ferromagnetic metla thin film layer contains oxygen and is formed on the flexible substrate which has been plasma treated at a frequency in the range of 10 to 200 kilohertz, and
- the medium has in average at least 10.sup.5 /a.sup.2 protrusions per square millimeter of the surface, the protrusions having a height of 30 to 300 .ANG., where a is the distance of the magnetic head gap and is 0.1 to 0.5 .mu.m.
Dependencies are inferred from the claim text.