中国物理B ›› 2004, Vol. 13 ›› Issue (9): 1553-1559.doi: 10.1088/1009-1963/13/9/033

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Vortex domain structures and dc current dependence of magneto-resistances in magnetic tunnel junctions

路庆凤1, 魏红祥2, 赵素芬3, 张谢群3, 丰家峰3, 韩秀峰3   

  1. (1)Department of Physics and Communication, Henan Normal University, Xinxiang 453002, China; (2)Department of Physics and Communication, Henan Normal University, Xinxiang 453002, China; State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China; (3)State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
  • 收稿日期:2004-04-13 修回日期:2004-06-18 出版日期:2004-06-21 发布日期:2005-06-21

Vortex domain structures and dc current dependence of magneto-resistances in magnetic tunnel junctions

Wei Hong-Xiang (魏红祥)ab, Lu Qing-Feng (路庆凤)a, Zhao Su-Fen (赵素芬)b, Zhang Xie-Qun (张谢群)b, Feng Jia-Feng (丰家峰)b, Han Xiu-Feng (韩秀峰)b   

  1. a Department of Physics and Communication, Henan Normal University, Xinxiang 453002, China; b State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
  • Received:2004-04-13 Revised:2004-06-18 Online:2004-06-21 Published:2005-06-21

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摘要： Microfabrication and the magneto-transport characteristics of the magnetic tunnel junctions (MTJs) with a spin-valve-type structure of Ta (5nm)/Ni_{79}Fe_{21} (25nm)/Ir_{22}Mn_{78} (12nm)/Co_{75}Fe_{25} (4nm)/Al(0.8nm) oxide/Co_{75}Fe_{25} (4nm)/Ni_{79}Fe_{21} (20nm)/Ta(5nm) were investigated in this paper. A series of experimental data measured with a MTJ was used to verify a magnon-assisted tunnelling model and theory. Furthermore, a micromagnetics simulation shows that the butterfly-like vortex domain structures can be formed under a current-induced Oersted field, which decreases the net magnetization values of the ferromagnetic electrodes under a large dc current (i.e., in high voltage regimes). It is one of the main reasons for the tunnel magnetoresistance ratios to decrease significantly at high voltage biasing.

关键词: magnetic tunnel junction, tunnel magnetorisistance, spin-electron transport, magnon-assisted tunnelling, vortex domain structure

Abstract: Microfabrication and the magneto-transport characteristics of the magnetic tunnel junctions (MTJs) with a spin-valve-type structure of Ta (5nm)/Ni$_{79}$Fe$_{21}$ (25nm)/Ir$_{22}$Mn$_{78}$ (12nm)/Co$_{75}$Fe$_{25}$ (4nm)/Al(0.8nm) oxide/Co$_{75}$Fe$_{25}$ (4nm)/Ni$_{79}$Fe$_{21}$ (20nm)/Ta(5nm) were investigated in this paper. A series of experimental data measured with a MTJ was used to verify a magnon-assisted tunnelling model and theory. Furthermore, a micromagnetics simulation shows that the butterfly-like vortex domain structures can be formed under a current-induced Oersted field, which decreases the net magnetization values of the ferromagnetic electrodes under a large dc current (i.e., in high voltage regimes). It is one of the main reasons for the tunnel magnetoresistance ratios to decrease significantly at high voltage biasing.

Key words: magnetic tunnel junction, tunnel magnetorisistance, spin-electron transport, magnon-assisted tunnelling, vortex domain structure

中图分类号:  (Metals and alloys)

  • 75.47.Np
72.15.Gd (Galvanomagnetic and other magnetotransport effects) 75.60.Ch (Domain walls and domain structure) 75.60.Ej (Magnetization curves, hysteresis, Barkhausen and related effects) 75.30.Ds (Spin waves) 71.70.Ej (Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect) 75.10.Jm (Quantized spin models, including quantum spin frustration)