The dependence of magnetic properties on layer repetition number and Ru thicknesses have been studied for perpendicularly magnetized synthetic antiferromagnet (SAF) in a structure of [Co/Ni]N/Ru/[Co/Ni] 3. The optimum SAF with strong antiferromangetic coupling field and large switching field of the net magnetization have been determined and utilized as the reference layer in the pseudo spin valves. Compared with the rapid drop of GMR signal for the normal [Co/Ni]-based pseudo spin valves after annealing at low temperature (Ta) of 150°C, the spin valve with SAF reference layer exhibits much stable thermal stability due to the large switching field difference between the free and reference layers which avoids the simultaneous magnetization rotation. The GMR signal of the SAF spin valve sample is 6.0% at room temperature, it decreases very gradually with the increase of T a. We attribute the slow GMR reduction observed in the SAF spin valve to the effects of domain formation and perpendicular anisotropy deterioration caused by high temperature anneals.
Bibliographical noteFunding Information:
This work was supported by the National Natural Science Foundation of China under Grants 50771033, 50771032, 10604016, and 60678008, the National Basic Research Program of China under Grant 2009CB929201, and the Innovation Program of Shanghai Municipal Education Commission under Grant 09ZZ03.
- GMR effect
- Perpendicular anisotropy
- Synthetic antiferromagnet
- Thermal stability