Magnetic recording medium having three ferromagnetic layers with increasing intrinsic coercivity from the lower to the upper layer
US7180710B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 24, 2004 |
| Grant date | Feb 20, 2007 |
| Priority date | — |
| Expiry date | Aug 5, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/82
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A magnetic recording medium has a laminated magnetic structure with at least three magnetic layers, wherein the magnetic layers have decreasing intrinsic coercivity H0 with distance from the write head. The write field at the center of each magnetic layer is greater than that layer's H0. The magnetic layers have different compositions and/or thicknesses and thereby different values of H0. The alloys used in the middle and upper magnetic layers are relatively “high-moment” alloys that would not ordinarily be used in magnetic recording media because they have relatively low S0NR, but the overall S0NR of the laminated magnetic structure is improved because of the effect of lamination. The middle and upper magnetic layers can be made substantially thinner, which enables the magnetic layers to be located closer to the write head, thereby exposing each of the magnetic layers to a higher write field.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.