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US 2003/0143434 A1Published application
Perpendicular magnetic recording medium
AssigneeToda Kogyo Corporation
InventorsJun Koujima, Teruaki Santoki, Masaaki Maekawa, Takanori Doi
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Abstract
A perpendicular magnetic recording medium, comprises a substrate; a soft-magnetic layer formed on the substrate; an NaCl-type oxide layer for orientation control formed on the soft-magnetic layer, having a thickness of from more than 0 to less than 10 nm; and a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film. Such a perpendicular magnetic recording medium is capable of showing excellent magnetic properties, a high recording resolution and improved surface properties.
Claims24
A perpendicular magnetic recording medium, comprising:
- a substrate;
- a soft-magnetic layer formed on the substrate;
- an NaCl-type oxide layer for orientation control formed on the soft-magnetic layer, having a thickness of from more than 0 to less than 10 nm;
- and
- a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film.
2 more elements
A perpendicular magnetic recording medium, comprising:
- a substrate;
- an NaCl-type oxide layer for orientation control formed on the substrate, having a thickness of from more than 0 to less than 10 nm;
- and
- a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film, and
- said perpendicular magnetic recording medium having a coercive force in perpendicular direction of not less than 159 kA/m (2,000 Oe);
- a squareness (Mr/Ms) of not less than 0.7 obtained without compensation of demagnetizing field when magnetized in a direction perpendicular to surface of the magnetic recording layer;
- an Mr ratio (Mr///Mr⊥) of a residual magnetization (Mr//) obtained when magnetized in in-plane direction to a residual magnetization (Mr⊥) obtained when magnetized in perpendicular direction, of not more than 0.5;
- and an Hc ratio (Hc///Hc⊥) of a coercive force (Hc//) obtained when magnetized in in-plane direction to a coercive force (Hc⊥) obtained when magnetized in perpendicular direction, of not more than 0.5.
5 more elements
A perpendicular magnetic recording medium, comprising:
- a substrate;
- a soft-magnetic layer formed on the substrate;
- an NaCl-type oxide layer for orientation control formed on the soft-magnetic layer, having a thickness of from more than 0 to less than 10 nm and a spacing of (200) plane larger than an inherent spacing (0.2086 nm) of (400) plane of maghemite constituting the magnetic recording layer;
- and
- a magnetic, recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film.
2 more elements
A perpendicular magnetic recording medium, comprising:
- a substrate;
- a soft-magnetic layer formed on the substrate, having a product (Bs·t) of a saturation magnetic flux density (Bs) and a thickness (t) of the soft-magnetic layer of 1.13 to 13.57×10−6 Wb/m (80 to 1,100 G·μm);
- an NaCl-type oxide layer for orientation control formed on the soft-magnetic layer, having a thickness of from more than 0 to less than 10 nm and a spacing of (200) plane larger than an inherent spacing (0.2086 nm) of (400) plane of maghemite constituting the magnetic recording layer;
- and
- a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film.
2 more elements
A perpendicular magnetic recording medium, comprising:
- a substrate;
- a soft-magnetic layer formed on the substrate, having a product (Bs·t) of a saturation magnetic flux density (Bs) and a thickness (t) of the soft-magnetic layer being in the range of 1.13 to 13.57×10−Wb/m (80 to 1,100 G·μm);
- an NaCl-type oxide layer for orientation control formed on the soft-magnetic layer, having a thickness of from more than 0 to less than 10 nm and a spacing of (200) plane larger than an inherent spacing (0.2086 nm) of (400) plane of maghemite constituting the magnetic recording layer;
- and
- a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film, and
- said perpendicular magnetic recording medium having a coercive force in perpendicular direction of not less than 159 kA/m (2,000 Oe);
- a squareness (Mr/Ms) of not less than 0.7 obtained without compensation of demagnetizing field when magnetized in a direction perpendicular to surface of the magnetic recording layer;
- an Mr ratio (Mr///Mr⊥) of a residual magnetization (Mr//) obtained when magnetized in in-plane direction to a residual magnetization (Mr⊥) obtained when magnetized in perpendicular direction, of not more than 0.5;
- and an Hc ratio (Hc///Hc⊥) of a coercive force (Hc//) obtained when magnetized in in-plane direction to a coercive force (Hc⊥) obtained when magnetized in perpendicular direction, of not more than 0.5.
6 more elements
A perpendicular magnetic recording medium, comprising:
- a substrate;
- a soft-magnetic layer formed on the substrate, having a product (Bs·t) of a saturation magnetic flux density (Bs) and a thickness (t) of the soft-magnetic layer being in the range of 1.13 to 13.57×10−6 Wb/m (80 to 1,100 G·μm);
- an NaCl-type oxide layer for orientation control formed on the soft-magnetic layer, having a thickness of from more than 0 to less than 10 nm and a spacing of (200) plane larger than an inherent spacing (0.2086 nm) of (400) plane of maghemite constituting the magnetic recording layer;
- and
- a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film and having a center-line mean roughness (Ra) of 0.1 to 1.5 nm and a maximum height (Rmax) of 1 to 15 nm, and
- said perpendicular magnetic recording medium having a coercive force in perpendicular direction of not less than 159 kA/m (2,000 Oe);
- a squareness (Mr/Ms) of not less than 0.7 obtained without compensation of demagnetizing field when magnetized in a direction perpendicular to surface of the magnetic recording layer;
- an Mr ratio (Mr///Mr⊥) of a residual magnetization (Mr//) obtained when magnetized in in-plane direction to a residual magnetization (Mr⊥) obtained when magnetized in perpendicular direction, of not more than 0.5;
- and an Hc ratio (Hc///Hc⊥) of a coercive force (Hc//) obtained when magnetized in in-plane direction to a coercive force (Hc⊥) obtained when magnetized in perpendicular direction, of not more than 0.5.
6 more elements
A perpendicular magnetic recording medium, comprising:
- a substrate;
- a soft-magnetic layer formed on the substrate, having a product (Bs·t) of a saturation magnetic flux density (Bs) and a thickness (t) of the soft-magnetic layer being in the range of 1.13 to 13.57×10−Wb/m (80 to 1,100 G·μm);
- an NaCl-type oxide layer for orientation control formed on the soft-magnetic layer, having a thickness of from more than 0 to less than 10 nm and a spacing of (200) plane larger than an inherent spacing (0.2086 nm) of (400) plane of maghemite constituting the magnetic recording layer;
- and
- a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film and having a center-line mean roughness (Ra) of 0.1 to 1.5 nm and a maximum height (Rmax) of 1 to 15 nm, and
- said perpendicular magnetic recording medium having a coercive force in perpendicular direction of not less than 159 kA/m (2,000 Oe);
- a squareness (Mr/Ms) of not less than 0.7 obtained without compensation of demagnetizing field when magnetized in a direction perpendicular to surface of the magnetic recording layer;
- an Mr ratio (Mr///Mr⊥) of a residual magnetization (Mr//) obtained when magnetized in in-plane direction to a residual magnetization (Mr⊥) obtained when magnetized in perpendicular direction, of not more than 0.5;
- an Hc ratio (Hc///Hc⊥) of a coercive force (Hc//) obtained when magnetized in in-plane direction to a coercive force (Hc⊥) obtained when magnetized in perpendicular direction, of not more than 0.5;
- and an electrical resistance of 100 to 8,000 kΩ in the case of using the soft-magnetic layer made of metal or alloy, or 100 to 30,000 MΩ in the case of using the soft-magnetic layer made of an oxide.
7 more elements
A perpendicular magnetic recording medium, comprising:
- a substrate;
- an NaCl-type oxide layer for orientation control formed on the substrate, having a thickness of from more than 0 to less than 10 nm and an inherent spacing of (200) plane larger than a spacing (0.2086 nm) of (400) plane of maghemite constituting the magnetic recording layer;
- and
- a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film and having a center-line mean roughness (Ra) of 0.1 to 1.5 nm and a maximum height (Rmax) of 1 to 15 nm,
- said perpendicular magnetic recording medium having a coercive force in perpendicular direction of not less than 159 kA/m (2,000 Oe);
- a squareness (Mr/Ms) of not less than 0.7 obtained without compensation of demagnetizing field when magnetized in a direction perpendicular to surface of the magnetic recording layer;
- an Mr ratio (Mr///Mr⊥) of a residual magnetization (Mr//) obtained when magnetized in in-plane direction to a residual magnetization (Mr⊥) obtained when magnetized in perpendicular direction, of not more than 0.5;
- and an Hc ratio (Hc///Hc⊥) of a coercive force (Hc//) obtained when magnetized in in-plane direction to a coercive force (Hc⊥) obtained when magnetized in perpendicular direction, of not more than 0.5.
5 more elements
A perpendicular magnetic recording medium, comprising:
- a substrate;
- an NaCl-type oxide layer for orientation control formed on the substrate, having a thickness of from more than 0 to less than 10 nm and an inherent spacing of (200) plane larger than a spacing (0.2086 nm) of (400) plane of maghemite constituting the magnetic recording layer;
- and
- a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film and having a center-line mean roughness (Ra) of 0.1 to 1.5 nm and a maximum height (Rmax) of 1 to 15 nm,
- said perpendicular magnetic recording medium having a coercive force in perpendicular direction of not less than 159 kA/m (2,000 Oe);
- a squareness (Mr/Ms) of not less than 0.7 obtained without compensation of demagnetizing field when magnetized in a direction perpendicular to surface of the magnetic recording layer;
- an Mr ratio (Mr///Mr⊥) of a residual magnetization (Mr//) obtained when magnetized in in-plane direction to a residual magnetization (Mr⊥) obtained when magnetized in perpendicular direction, of not more than 0.5;
- and an Hc ratio (Hc///Hc⊥) of a coercive force (Hc//) obtained when magnetized in in-plane direction to a coercive force (Hc⊥) obtained when magnetized in perpendicular direction, of not more than 0.5.
5 more elements
Dependencies are inferred from the claim text.