Perpendicular magnetic recording medium with exchange-spring structure having multiple exchange-spring layers and recording system for the medium
US7572526B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 18, 2007 |
| Grant date | Aug 11, 2009 |
| Priority date | — |
| Expiry date | Sep 1, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/678
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A perpendicular magnetic recording system uses an exchange-spring type of perpendicular magnetic recording medium. The medium has a recording layer (RL) that includes a lower media layer (ML) and a multilayer exchange-spring layer (ESL) above the ML. The high anisotropy field (high-Hk) lower ML and the multilayer ESL are exchange-coupled across a coupling layer. The multilayer ESL has at least two ESLs separated by a coupling layer, with each of the ESLs having an Hk substantially less than the Hk of the ML. The exchange-spring structure with the multilayer ESL takes advantage of the fact that the write field magnitude and write field gradient vary as a function of distance from the write pole. The thicknesses and Hk values of each of the ESLs can be independently varied to optimize the overall recording performance of the medium.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.