1School of Microelectronic and Solid-state Electronic, University of Electronic Science and Technology of China, Chengdu 610054
2Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
Effects of Layer Deposition Sequence on Microstructure and Magnetostatic Coupling of Spin-Valves with Amorphous CoNbZr Layer
WEN Qi-Ye1;ZHANG Huai-Wu1;JIANG Xiang-Dong1;TANG Xiao-Li1; ZHONG Zhi-Yong1; John Q. Xiao2
1School of Microelectronic and Solid-state Electronic, University of Electronic Science and Technology of China, Chengdu 610054
2Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
Abstract： We investigate spin-valve sandwiches with thin amorphous CoNbZr as soft layers. The magnetoresistance (MR), microstructure, and magnetostatic coupling are studied in these sandwiches with different layer deposition sequences. For the CoNbZr/Cu/Co sandwich, the CoNbZr underlayer provides a smoother surface on which smooth Cu and Co layers can subsequently grow. The Cu spacer is dense and pinholes-free, leading to a good ``spin valve'' effect with a larger MR ratio of 3.8%. For the Co/Cu/CoNbZr sandwich, however, the Cu spacer is rough and pinholes were observed, which could induce a direct ferromagnetic coupling. Correlated rougher surfaces on both the sides of the Cu spacer were also observed, giving rise to an ``orangepeel'' coupling of
about 0.105erg/cm-2. This strong ferromagnetic coupling in Co/Cu/CoNbZr results in a lower MR ratio of 1.6%. Moreover, upon proper thermal annealing, the CoNbZr/Cu/Co has a larger MR enhancement and a superior thermal stability to 350°C due to the dense and homogenous structure in the spacer layer.
2005, Vol. 22 
