Improvement of Thermal Tolerance of CoFeB-MgO Perpendicular-Anisotropy Magnetic Tunnel Junctions by Controlling Boron Composition

H. Honjo, S. Ikeda, H. Sato, S. Sato, T. Watanabe, S. Miura, T. Nasuno, Y. Noguchi, M. Yasuhira, T. Tanigawa, H. Koike, M. Muraguchi, M. Niwa, K. Ito, H. Ohno, T. Endoh

研究成果: Article査読

11 被引用数 (Scopus)

抄録

We investigated annealing temperature $T-{a}$ dependence of tunnel magnetoresistance (TMR) ratio and magnetic properties for perpendicular-anisotropy (CoFe)100-XBX/MgO magnetic tunnel junctions (MTJs) with single (CoFe)100-XBX/MgO interface (s-MTJ) and double CoFeB-MgO interface (d-MTJ) structures with various boron compositions X. High TMR ratio over 100% was observed in the s-MTJ with X=35 at.% after annealing at 360 °C-400 °C, whereas the s-MTJ with X=30 at.% showed the degradation of TMR ratio with the increase of Ta above 360 °C, resulting from the decrease of perpendicular anisotropy. The d-MTJ with X=25 at.% maintained high TMR ratio up to Ta = 400°C owing to its higher perpendicular anisotropy compared with the s-MTJ. The difference of perpendicular anisotropy between the s-MTJ and the d-MTJ can be attributed to higher interfacial anisotropy together with lower saturation magnetization of the d-MTJs. The lower saturation magnetization is attributable to two MgO layers that suppress boron diffusion from CoFeB layers, which was verified by cross-sectional line analysis using electron energy-loss spectroscopy.

本文言語English
論文番号7383297
ジャーナルIEEE Transactions on Magnetics
52
7
DOI
出版ステータスPublished - 2016 7

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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