Perpendicular magnetic recording medium
US8323808B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Jan 10, 2005 |
| Grant date | Dec 4, 2012 |
| Priority date | — |
| Expiry date | May 21, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/672
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
There is provided a perpendicular magnetic recording medium according to which both the thermal stability of the magnetization is good and writing with a magnetic head is easy, and moreover the SNR is improved. In the case of a perpendicular magnetic recording medium comprising a nonmagnetic substrate 1, and at least a nonmagnetic underlayer 2, a magnetic recording layer 3 and a protective layer 4 formed in this order on the nonmagnetic substrate 1, the magnetic recording layer 3 comprises a low Ku region 31 layer having a perpendicular magnetic anisotropy constant (Ku value) of not more than 1×105 erg/cm3, and a high Ku region 32 layer having a Ku value of at least 1×106 erg/cm3. Moreover, the magnetic recording layer 3 is made to have therein nonmagnetic grain boundaries that contain a nonmagnetic oxide and magnetically isolate crystal grains, which are made of a ferromagnetic metal, from one another.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.