Magnetic tunnel junction structure and method
US7572645B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 15, 2006 |
| Grant date | Aug 11, 2009 |
| Priority date | — |
| Expiry date | Feb 8, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10N50/10
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Methods and apparatus are provided for magnetic tunnel junctions (MTJs) (10, 50) employing synthetic antiferromagnet (SAF) free layers (14, 14′). The MTJ (10, 50) comprises a pinned ferromagnetic (FM) layer (32, 18), the SAF (14) and a tunneling barrier (16) therebetween. The SAF (14) has a first higher spin polarization FM layer (30) proximate the tunneling barrier (16) and a second FM layer (26) desirably separated from the first FM layer (30) by a coupling layer (28), with magnetostriction adapted to compensate the magnetostriction of the first FM layer (30). Such compensation reduces the net magnetostriction of the SAF (14) to near zero even with high spin polarization proximate the tunneling barrier (16). Higher magnetoresistance ratios (MRs) are obtained without adverse affect on other MTJ (10, 50) properties. NiFe combinations are desirable for the first (30) and second (26) free FM layers, with more Fe in the first (30) free layer and less Fe in the second (26) free layer. CoFeB and NiFeCo are also useful in the free layers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.