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http://dx.doi.org/10.4283/JMAG.2005.10.4.137

Effect of Thermal Treatment on AIOx/Co90Fe10 Interface of Magnetic Tunnel Junctions Prepared by Radical Oxidation  

Lee, Don-Koun (Ceramic Engineering, Advanced Materials Engineering, Yonsei University)
In, Jang-Sik (Ceramic Engineering, Advanced Materials Engineering, Yonsei University)
Hong, Jong-Ill (Ceramic Engineering, Advanced Materials Engineering, Yonsei University)
Publication Information
Journal of Magnetics / v.10, no.4, 2005 , pp. 137-141 More about this Journal
Abstract
We confirmed that the improvement in properties of magnetic tunnel junctions prepared by radical oxidation after thermal treatment was mostly resulted from the redistribution of oxygen at the $AIOx/Co_{90}Fe_{10}$ interface. The as-deposited Al oxide barrier was oxygen-deficient but most of it re-oxidized into $Al_2O_3$, the thermodynamically stable stoichiometric phase, through thermal treatment. As a result, the effective barrier height was increased from 1.52 eV to 2.27 eV. On the other hand, the effective barrier width was decreased from 8.2 ${\AA}$ to 7.5 ${\AA}$. X-ray absorption spectra of Fe and Co clearly showed that the oxygen in the CoFe layer diffused back into the Al barrier and thereby enriched the barrier to close to a stoichiometirc $Al_2O_3$ phase. The oxygen bonded with Co and Fe diffused back by 6.8 ${\AA}$ and 4.5 ${\AA}$ after thermal treatment, respectively. Our results confirm that controlling the chemical structures of the interface is important to improve the properties of magnetic tunnel junctions.
Keywords
tunneling magnetoresistance; Fe oxide; Co oxide; x-ray absorption spectroscopy; chemical fine structure;
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