Perpendicular magnetic recording medium
US8691402B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Nov 2, 2012 |
| Grant date | Apr 8, 2014 |
| Priority date | — |
| Expiry date | Nov 2, 2032 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/672
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
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.