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arXiv · 0910.4204

MgO barrier-perpendicular magnetic tunnel junctions with CoFe/Pd multilayers and ferromagnetic insertion layers

K. Mizunuma·S. Ikeda·J. H. Park·H. Yamamoto·H. Gan·K. Miura·H. Hasegawa·J. Hayakawa·F. Matsukura·H. Ohno
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Abstract

The authors studied an effect of ferromagnetic (Co20Fe60B20 or Fe) layer insertion on tunnel magnetoresistance (TMR) properties of MgO-barrier magnetic tunnel junctions (MTJs) with CoFe/Pd multilayer electrodes. TMR ratio in MTJs with CoFeB/MgO/Fe stack reached 67% at an-nealing temperature (Ta) of 200 degree C and then decreased rapidly at Ta over 250 degree C. The degradation of the TMR ratio may be related to crystallization of CoFe(B) into fcc(111) or bcc(011) texture result-ing from diffusion of B into Pd layers. MTJs which were in-situ annealed at 350oC just after depo-siting bottom CoFe/Pd multilayer showed TMR ratio of 78% by post annealing at Ta =200 degree C.

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K. Mizunuma, S. Ikeda, J. H. Park, H. Yamamoto, H. Gan, K. Miura, H. Hasegawa, J. Hayakawa, F. Matsukura, H. Ohno. 2009-10-22. MgO barrier-perpendicular magnetic tunnel junctions with CoFe/Pd multilayers and ferromagnetic insertion layers. https://doi.org/10.1063/1.3265740

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