The exchange-coupled [Co/Ni]N/TbFe nano-magnetic films can display strong perpendicular magnetic anisotropy (PMA) which depends on the Tb:Fe component ratio, TbFe layer thickness and the repetition number N of [Co/ Ni]N multilayer. Perpendicular spin valves in the nano thickness scale, consisting of a [Co/Ni]3 free and a [Co/Ni]5/TbFe reference multilayer, show high giant magnetoresistance (GMR) signal of 6.5 % and a large switching field difference over 3 kOe. However, unexpected slanting of the free layer magnetization, accompanied by a reduced GMR ratio, was found to be caused by the presence of a thick Fe-rich or even a thin but Tb-rich TbFe layer. We attribute this phenomenon to the large magnetostriction effect of TbFe which probably induces strong stress acting on the free layer and hence reduces its interfacial PMA.
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Acknowledgments This work is supported by the National Basic Research Program of China (2014CB921104), and the National Natural Science Foundation of China (Grant Nos. 51222103, 11274113, 11474067, and 51171047). Z. Zhang thanks for the support from the Program for New Century Excellent Talents in University (NCET-12-0132).
©The Author(s) 2014.
- Nano magnetic films
- Perpendicular magnetic anisotropy
- Spin valves