Perpendicular magnetic recording medium with laminated recording layers formed of exchange-coupled ferromagnetic layers
US7488545B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 12, 2006 |
| Grant date | Feb 10, 2009 |
| Priority date | — |
| Expiry date | Apr 12, 2026 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/676
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A laminated perpendicular magnetic recording medium has two recording layers (RL1 and RL2) that are separated and magnetically decoupled by a nonmagnetic spacer layer (SL). The SL has a thickness and composition to assure there is no antiferromagnetic or ferromagnetic coupling between RL1 and RL2. Thus in the presence of the write field, RL1 and RL2 respond independently and become oriented with the direction of the write field. Each RL is an “exchange-spring” type magnetic recording layer formed of two ferromagnetic layers (MAG1 and MAG2) that have substantially perpendicular magnetic anisotropy and are ferromagnetically exchange-coupled by a nonmagnetic or weakly ferromagnetic coupling layer (CL). The medium takes advantage of lamination to attain higher signal-to-noise ratio (SNR) yet has improved writability as a result of each RL being an exchange-spring type RL.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.