Perpendicular magnetic recording medium with improved antiferromagnetically-coupled recording layer
US7572527B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 24, 2005 |
| Grant date | Aug 11, 2009 |
| Priority date | — |
| Expiry date | Feb 21, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/7368
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A perpendicular magnetic recording disk has an antiferromagnetically-coupled (AFC) recording layer (RL) comprised of lower and upper ferromagnetic layers, each having a hexagonal-close-packed (hcp) crystalline structure and perpendicular magnetic anisotropy, separated by an antiferromagnetically (AF) coupling layer, wherein the lower ferromagnetic layer (LFM) has substantially higher magnetic permeability than the upper ferromagnetic layer (UFM). The AFC RL is located on an actual exchange break layer (EBL) that separates the AFC RL from the disk's soft magnetic underlayer (SUL). The LFM functions as part of an “effective” exchange break layer (EBL) that also includes the actual EBL and the AF-coupling layer, thereby allowing the actual EBL to be made as thin as possible. The hcp LFM promotes the growth of the hcp UFM in the same way the actual EBL does so that its thickness contributes to the thickness necessary to grow the hcp UFM. The effective EBL appears to be magnetically “thin” during the write process and magnetically “thick” during the readback process.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.