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The absence of exchange bias with (001)-oriented tetragonal-like BiFeO3 films

Authors

  • Qingyu Xu,

    Corresponding author
    1. Department of Physics, Southeast University, Nanjing, P. R. China
    2. Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing, P. R. China
    3. National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, P. R. China
    • Corresponding author: e-mail xuqingyu@nju.edu.cn, Phone: +86 2552090600, ext: 8308, Fax: +86 2552090600, ext: 8308

      e-mail: jdu@nju.edu.cn, Phone: +86 2583592762, Fax: +86 2583595535

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  • Xueyong Yuan,

    1. Department of Physics, Southeast University, Nanjing, P. R. China
    2. Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing, P. R. China
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  • Xiaobo Xue,

    1. National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, P. R. China
    2. Department of Physics, Nanjing University, Nanjing, P. R. China
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  • Zhong Shi,

    1. Department of Physics, Tongji University, Shanghai, P. R. China
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  • Zheng Wen,

    1. Department of Materials Science and Engineering, Nanjing University, Nanjing, P. R. China
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  • Jun Du

    Corresponding author
    1. National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, P. R. China
    2. Department of Physics, Nanjing University, Nanjing, P. R. China
    • Corresponding author: e-mail xuqingyu@nju.edu.cn, Phone: +86 2552090600, ext: 8308, Fax: +86 2552090600, ext: 8308

      e-mail: jdu@nju.edu.cn, Phone: +86 2583592762, Fax: +86 2583595535

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Abstract

Single-phase tetragonal-like BiFeO3 (T-BFO) films with thickness up to 480 nm have been successfully prepared on (001) LaAlO3 substrates using NdAlO3 (NAO) as a buffer layer. The monoclinic distortion increases on increasing the thickness of T-BFO films. Negligible small exchange bias field (HE) (<8 Oe) has been observed in T-BFO/NiFe bilayers. The insertion of a 2-nm thick La0.67Sr0.33MnO3 (LSMO) film between NAO and BFO can keep the structure of single-phase T-BFO. Strongly enhanced HE and coercivity has been observed below 100 K in LSMO/T-BFO bilayer, which has been attributed to the phase separation and coexistence of antiferromagnetic and ferromagnetic phases in the ultrathin LSMO layer due to the compressive strain exerted by the NAO buffer layer. Our results clearly demonstrate that T-BFO cannot provide an effective exchange bias field on the adjacent ferromagnetic layer, and the possible explanation has been provided.

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