Magnetic sensors having antiferromagnetically exchange-coupled layers for longitudinal biasing
US6266218A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 28, 1999 |
| Grant date | Jul 24, 2001 |
| Priority date | — |
| Expiry date | Oct 28, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2005/3996
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A longitudinal bias structure to be placed adjacent a ferromagnetic free layer or a sense layer which is responsive to an external magnetic field and belongs to a magnetic sensor, for example a magnetic readback sensor such as an anisotropic magnetoresistive (AMR) sensor, giant magnetoresistive (GMR) sensor such as GMR spin valve sensor or GMR multilayer sensor or in tunnel valve sensor. The longitudinal bias structure is built up of a top ferromagnetic bias layer of first thickness t.sub.1 having a first magnetic moment M.sub.1, a bottom ferromagnetic bias layer of second thickness t.sub.2 having a second magnetic moment M.sub.2 which is anti-parallel to first magnetic moment M.sub.1 of the top ferromagnetic bias layer, and an exchange-coupling layer disposed between the top and bottom bias layers. In this configuration the top ferromagnetic bias layer and the bottom ferromagnetic bias layer are antiferromagnetically coupled by the exchange-coupling layer and the remnant magnetization thickness product of the bias structure is desirably low and equal to M.sub.1 t.sub.1 -M.sub.2 t.sub.2. The longitudinal bias structure can further include an antiferromagnetic layer next to one of t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.