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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
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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.

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Jun Hayakawa, Shoji Ikeda, Young Min Lee, Ryutaro Sasaki, Toshiyasu Meguro, Fumihiro Matsukura, Hiromasa Takahashi, Hideo Ohno. 2006-09-28. Current-induced magnetization switching in MgO barrier based magnetic tunnel junctions with CoFeB/Ru/CoFeB synthetic ferrimagnetic free layer. https://doi.org/10.1143/jjap.45.l1057

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