Current-induced magnetization switching in MgO barrier based magnetic tunnel junctions with CoFeB/Ru/CoFeB synthetic ferrimagnetic free layer

Jun Hayakawa; Shoji Ikeda; Young Min Lee; Ryutaro Sasaki; Toshiyasu Meguro; Fumihiro Matsukura; Hiromasa Takahashi; Hideo Ohno

doi:10.1143/JJAP.45.L1057

Current-induced magnetization switching in MgO barrier based magnetic tunnel junctions with CoFeB/Ru/CoFeB synthetic ferrimagnetic free layer

Materials Science 2009-11-11 v2

Authors: Jun Hayakawa , Shoji Ikeda , Young Min Lee , Ryutaro Sasaki , Toshiyasu Meguro , Fumihiro Matsukura , Hiromasa Takahashi , Hideo Ohno

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Abstract

We report the intrinsic critical current density (Jc0) in current-induced magnetization switching and the thermal stability factor (E/kBT, where E, kB, and T are the energy potential, the Boltzmann constant, and temperature, respectively) in MgO based magnetic tunnel junctions with a Co40Fe40B20(2nm)/Ru(0.7-2.4nm)/Co40Fe40B20(2nm) synthetic ferrimagnetic (SyF) free layer. We show that Jc0 and E/kBT can be determined by analyzing the average critical current density as a function of coercivity using the Slonczewski's model taking into account thermal fluctuation. We find that high antiferromagnetic coupling between the two CoFeB layers in a SyF free layer results in reduced Jc0 without reducing high E/kBT.

Keywords

magnetic tunnel junctions current-induced magnetization switching synthetic ferrimagnetic free layer critical current density thermal stability MgO barrier

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@article{arxiv.cond-mat/0609306,
  title  = {Current-induced magnetization switching in MgO barrier based magnetic tunnel junctions with CoFeB/Ru/CoFeB synthetic ferrimagnetic free layer},
  author = {Jun Hayakawa and Shoji Ikeda and Young Min Lee and Ryutaro Sasaki and Toshiyasu Meguro and Fumihiro Matsukura and Hiromasa Takahashi and Hideo Ohno},
  journal= {arXiv preprint arXiv:cond-mat/0609306},
  year   = {2009}
}

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16 pages, 4 figures. Jpn. J. Appl. Phys., in press

Current-induced magnetization switching in MgO barrier based magnetic tunnel junctions with CoFeB/Ru/CoFeB synthetic ferrimagnetic free layer

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