MAGNETIC SIGNAL REPRODUCTION SYSTEM AND MAGNETIC SIGNAL REPRODUCTION METHOD

• US 20090027812A1
• Filed: 07/28/2008
• Published: 01/29/2009
• Est. Priority Date: 07/27/2007
• Status: Abandoned Application

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation), TDK Corporation
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation), TDK Corporation
• Inventors: Noguchi, Hitoshi, Endo, Yasushi, Shimizu, Osamu, Yoshida, Makoto, Maejima, Kazuhiko, Kawai, Mitsuyoshi
• Application Number:
  US12/180,580
• Publication Number:
  US 20090027812A1
• Time in Patent Office: Days
• US Class Current: 360/324.110
• CPC Class Codes: G11B 5/00826 comprising a plurality of single poles or gaps or groups thereof operative at the same time
• CPC Class Codes: G11B 5/29 Structure or manufacture of unitary devices formed of plural heads for more than one track G11B5/33, G11B5/49 and subgroups take precedence; in thin film structure G11B5/31
• CPC Class Codes: G11B 5/3106 where the integrated or assembled structure comprises means for conditioning against physical detrimental influence, e.g. wear, contamination G11B5/3133 takes precedence
• CPC Class Codes: G11B 5/3906 Details related to the use of magnetic thin film layers or to their effects
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/70678 Ferrites
• CPC Class Codes: G11B 5/7085 non-magnetic abrasive particles
• CPC Class Codes: G11B 5/71 characterised by the lubricant
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles

Abstract

The magnetic signal reproduction system comprises a magnetic recording medium comprising a magnetic layer comprising a ferromagnetic powder and a binder on a nonmagnetic support and a reproduction head, wherein a number of protrusions equal to or greater than 10 nm in height on the magnetic layer surface, as measured by an atomic force microscope, ranges from 50 to 2500/10,000 μm², a quantity of lubricant on the magnetic layer surface, denoted as a surface lubricant index, ranges from 0.5 to 5.0, a surface abrasive occupancy of the magnetic layer ranges from 2 to 20 percent, the reproduction head is a magnetoresistive magnetic head comprising a spin-valve layer, the spin-valve layer comprises a magnetization free layer, a magnetization pinned layer and an antiferromagnetic layer, and the antiferromagnetic layer is comprised of alloy comprising iridium and manganese, and the reproduction head comes in sliding contact with the magnetic recording medium during signal reproduction.

Claims

1. A magnetic signal reproduction system comprising:

a magnetic recording medium comprising a magnetic layer comprising a ferromagnetic powder and a binder on a nonmagnetic support; and

a reproduction head,

wherein

a number of protrusions equal to or greater than 10 nm in height on the magnetic layer surface, as measured by an atomic force microscope, ranges from 50 to 2500/10,000 μ

m²,

a quantity of lubricant on the magnetic layer surface, denoted as a surface lubricant index, ranges from 0.5 to 5.0,

a surface abrasive occupancy of the magnetic layer ranges from 2 to 20 percent,

the reproduction head is a magnetoresistive magnetic head comprising a spin-valve layer,

the spin-valve layer comprises a magnetization free layer, a magnetization pinned layer and an antiferromagnetic layer, and the antiferromagnetic layer is comprised of alloy comprising iridium and manganese, and

the reproduction head comes in sliding contact with the magnetic recording medium during signal reproduction.

2. The magnetic signal reproduction system according to claim 1, wherein the ferromagnetic powder is a hexagonal ferrite powder.

3. The magnetic signal reproduction system according to claim 2, wherein the hexagonal ferrite powder has a mean plate diameter ranging from 10 to 50 nm.

4. The magnetic signal reproduction system according to claim 1, wherein the magnetic layer has a thickness ranging from 10 to 150 nm.

5. A magnetic signal reproduction method reproducing signals, that have been recorded on a magnetic recording medium, with a reproduction head, wherein

the magnetic recording medium comprises a magnetic layer comprising a ferromagnetic powder and a binder on a nonmagnetic support,

a number of protrusions equal to or greater than 10 nm in height on the magnetic layer surface, as measured by an atomic force microscope, ranges from 50 to 2500/10,000 μ

m²,

a quantity of lubricant on the magnetic layer surface, denoted as a surface lubricant index, ranges from 0.5 to 5.0,

a surface abrasive occupancy of the magnetic layer ranges from 2 to 20 percent,

the reproduction head is a magnetoresistive magnetic head comprising a spin-valve layer,

the spin-valve layer comprises a magnetization free layer, a magnetization pinned layer and an antiferromagnetic layer, and the antiferromagnetic layer is comprised of alloy comprising iridium and manganese, and

the reproduction head comes in sliding contact with the magnetic recording medium during signal reproduction.

6. The magnetic signal reproduction method according to claim 5, wherein the ferromagnetic powder is a hexagonal ferrite powder.

7. The magnetic signal reproduction method according to claim 6, wherein the hexagonal ferrite powder has a mean plate diameter ranging from 10 to 50 nm.

8. The magnetic signal reproduction method according to claim 5, wherein the magnetic layer has a thickness ranging from 10 to 150 nm.