Soft magnetic characteristics of an ultrathin CoFeNi free layer in spin-valve films
Abstract
We have investigated the soft magnetic characteristics of an ultrathin Co-rich CoFeNi free layer in spin-valve films. By addition of Ni to a Co-rich CoFe free layer, magnetostriction ( λ) of the films increased positively with Ni concentration, in contrast to which a Co 90Fe 10 free layer showed a negatively large λ. However, Ni addition also caused an increase in coercivity of the easy axis direction ( Hce.a.). To avoid this problem, a slight decrease in the Co contents of a CoFeNi free layer was found to be effective for decreasing Hce.a.. In order to satisfy both the small λ and Hce.a., a free layer of (Co 86Fe 14) 88-94Ni 12-6 proved to be an optimum composition in spin-valve films. Moreover, the zero λ composition of the CoFeNi free layer was changed by a high-conductance Cu layer deposited on the free layer, which was considered to come from the lattice strain of a free layer.
- Publication:
-
Journal of Magnetism and Magnetic Materials
- Pub Date:
- March 2006
- DOI:
- 10.1016/j.jmmm.2005.03.010
- Bibcode:
- 2006JMMM..298...65F
- Keywords:
-
- 75.70.Ak;
- 75.70.Pa;
- 75.80.+q;
- 85.70.Kh;
- Magnetic properties of monolayers and thin films;
- Magnetomechanical and magnetoelectric effects magnetostriction;
- Magnetic thin film devices: magnetic heads;
- domain-motion devices etc.