Abstract
The influence of substrate temperature and annealing on quality/microstructural evolution of MgO, as well as the resultant magnetoresistance (MR) ratio, has been investigated. It has been found that the crystallinity of MgO in the MgO/NiFe/MgO heterostructures gradually improves with increasing substrate temperature. This behavior facilitates the transport of spin-polarized electrons, resulting in a high MR value. After annealing, the formation of vacancy clusters in MgO layers observed through positron annihilation spectroscopy leads to an increase in MR at different levels because of the crystallinity improvement of MgO. However, these vacancy clusters as another important defect can limit further improvement in MR.
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Acknowledgments
The present work was supported by the National Science Foundation of China (Grant No. 51071023, 51101047), the Natural Science Foundation of Hainan Province (No. 512114), the Ph.D. Programs Foundation of Ministry of Education (Grant No. 20120006130002), and PCSIRT.
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Zhao, CJ., Ding, L., Zhao, ZD. et al. Tuning the properties of an MgO layer for spin-polarized electron transport. Appl. Phys. A 116, 845–850 (2014). https://doi.org/10.1007/s00339-013-8178-1
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DOI: https://doi.org/10.1007/s00339-013-8178-1