System, method and apparatus for multiple anisotropy layered magnetic structures for controlling reversal mechanism and tightening of switching field distribution in bit patterned media
US8163405B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 27, 2009 |
| Grant date | Apr 24, 2012 |
| Priority date | — |
| Expiry date | May 29, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/82
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Multiple anisotropy layered magnetic structures for controlling reversal mechanism and tightening of switching field distribution in bit patterned media are disclosed. The invention extends the exchange spring concept to more variable and sophisticated structures. Three or more layers with different anisotropy or anisotropy gradients increase writeability gains beyond the simple hard/soft bilayer exchange spring concept for BPM. The structures have a thin very hard, high anisotropy center layer that acts as a threshold or pinning layer for domain wall propagation through the entire media structure. In addition or alternatively, a thin very soft, low anisotropy center layer in between the commonly used soft surface layer and hard media layer allows quick initial propagation of the domain wall into the center of the media structure. Various properties of the media structures can be tuned more independently for optimization if using more advanced multi-anisotropy layer stacks.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.