Magnetic recording medium and magnetic recording and reproducing device
US7976965B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 20, 2009 |
| Grant date | Jul 12, 2011 |
| Priority date | — |
| Expiry date | Aug 20, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/678
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A magnetic recording medium comprises a nonmagnetic substrate on which is disposed at least a vertical magnetic layer. The vertical magnetic layer comprises at least three layers including a lower layer, an intermediate layer and an upper layer from the substrate side. The lower, intermediate and upper magnetic layers are bound by ferro-coupling and are constituted of magnetic particles which are columnar crystals extending continuously from the lower layer to the upper layer. A nonmagnetic layer is between the lower and intermediate magnetic layers or between the intermediate and upper magnetic layers. The upper layer has a magnetic anisotropic constant (Ku) from 0.8×106 to 4×106 (erg/cc), the intermediate layer has a magnetic anisotropic constant (Ku) from 2×106 to 7×106 (erg/cc) and the lower layer has a magnetic anisotropic constant (Ku) from 1×106 to 4×106 (erg/cc).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.