中国物理B ›› 2015, Vol. 24 ›› Issue (7): 78504-078504.doi: 10.1088/1674-1056/24/7/078504

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Low frequency noise in asymmetric double barrier magnetic tunnel junctions with a top thin MgO layer

郭会强a, 唐伟跃a, 刘亮b c, 危健b c, 李大来d, 丰家峰d, 韩秀峰d   

  1. a School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China;
    b International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China;
    c Collaborative Innovation Center of Quantum Matter, Beijing, China;
    d Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2015-01-31 修回日期:2015-03-16 出版日期:2015-07-05 发布日期:2015-07-05
  • 基金资助:
    Project supported by the National Basic Research Program of China (Grant Nos. 2011CBA00106, 2012CB927400, 2010CB934401, and 2014AA032904), the National High Technology Research and Development Program of China (Grant No. 2014AA032904), and the National Natural Science Foundation of China (Grant Nos. 11434014 and 11104252).

Low frequency noise in asymmetric double barrier magnetic tunnel junctions with a top thin MgO layer

Guo Hui-Qiang (郭会强)a, Tang Wei-Yue (唐伟跃)a, Liu Liang (刘亮)b c, Wei Jian (危健)b c, Li Da-Lai (李大来)d, Feng Jia-Feng (丰家峰)d, Han Xiu-Feng (韩秀峰)d   

  1. a School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China;
    b International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China;
    c Collaborative Innovation Center of Quantum Matter, Beijing, China;
    d Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2015-01-31 Revised:2015-03-16 Online:2015-07-05 Published:2015-07-05
  • Contact: Tang Wei-Yue, Wei Jian E-mail:tangwy@zzu.edu.cn;weijian6791@pku.edu.cn
  • Supported by:
    Project supported by the National Basic Research Program of China (Grant Nos. 2011CBA00106, 2012CB927400, 2010CB934401, and 2014AA032904), the National High Technology Research and Development Program of China (Grant No. 2014AA032904), and the National Natural Science Foundation of China (Grant Nos. 11434014 and 11104252).

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摘要： Low frequency noise has been investigated at room temperature for asymmetric double barrier magnetic tunnel junctions (DBMTJs), where the coupling between the top and middle CoFeB layers is antiferromagnetic with a 0.8-nm thin top MgO barrier of the CoFeB/MgO/CoFe/CoFeB/MgO/CoFeB DBMTJ. At enough large bias, 1/f noise dominates the voltage noise power spectra in the low frequency region, and is conventionally characterized by the Hooge parameter αmag. With increasing external field, the top and bottom ferromagnetic layers are aligned by the field, and then the middle free layer rotates from antiparallel state (antiferromagnetic coupling between top and middle ferromagnetic layers) to parallel state. In this rotation process αmag and magnetoresistance-sensitivity-product show a linear dependence, consistent with the fluctuation dissipation relation. With the magnetic field applied at different angles (θ) to the easy axis of the free layer, the linear dependence persists while the intercept of the linear fit satisfies a cos(θ) dependence, similar to that for the magnetoresistance, suggesting intrinsic relation between magnetic losses and magnetoresistance.

关键词: magnetic tunnel junctions, double barrier magnetic tunnel junctions, 1/f noise, fluctuation dissipation relation

Abstract: Low frequency noise has been investigated at room temperature for asymmetric double barrier magnetic tunnel junctions (DBMTJs), where the coupling between the top and middle CoFeB layers is antiferromagnetic with a 0.8-nm thin top MgO barrier of the CoFeB/MgO/CoFe/CoFeB/MgO/CoFeB DBMTJ. At enough large bias, 1/f noise dominates the voltage noise power spectra in the low frequency region, and is conventionally characterized by the Hooge parameter αmag. With increasing external field, the top and bottom ferromagnetic layers are aligned by the field, and then the middle free layer rotates from antiparallel state (antiferromagnetic coupling between top and middle ferromagnetic layers) to parallel state. In this rotation process αmag and magnetoresistance-sensitivity-product show a linear dependence, consistent with the fluctuation dissipation relation. With the magnetic field applied at different angles (θ) to the easy axis of the free layer, the linear dependence persists while the intercept of the linear fit satisfies a cos(θ) dependence, similar to that for the magnetoresistance, suggesting intrinsic relation between magnetic losses and magnetoresistance.

Key words: magnetic tunnel junctions, double barrier magnetic tunnel junctions, 1/f noise, fluctuation dissipation relation

中图分类号:  (Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields)

  • 85.75.-d
73.50.Td (Noise processes and phenomena) 75.60.Jk (Magnetization reversal mechanisms)