中国物理B ›› 2005, Vol. 14 ›› Issue (3): 604-609.doi: 10.1088/1009-1963/14/3/032

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Dependence of the coercivity of La0.67Ca0.33MnO3 films on substrate and thickness

熊昌民, 孙继荣, 王登京, 刘光娟, 张宏伟, 沈保根   

  1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
  • 收稿日期:2004-08-31 修回日期:2004-11-16 出版日期:2005-03-02 发布日期:2005-03-02
  • 基金资助:
    Project supported by the Funds of Outstanding Young Researchers from the National Science Foundation of China (Grant No 50225209) and the State Key Project from the National Natural Science Foundation of China (Grant No 19934010).

Dependence of the coercivity of La0.67Ca0.33MnO3 films on substrate and thickness

Xiong Chang-Min (熊昌民), Sun Ji-Rong (孙继荣), Wang Deng-Jing (王登京), Liu Guan-Juan (刘光娟), Zhang Hong-Wei (张宏伟), Shen Bao-Gen (沈保根)   

  1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
  • Received:2004-08-31 Revised:2004-11-16 Online:2005-03-02 Published:2005-03-02
  • Supported by:
    Project supported by the Funds of Outstanding Young Researchers from the National Science Foundation of China (Grant No 50225209) and the State Key Project from the National Natural Science Foundation of China (Grant No 19934010).

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摘要： We investigate the effects of strain and film thickness on the coercivity of La0.67Ca0.33MnO3 films grown on SrTiO3 and LaAlO3 substrates. Textured microstructure with the grain [001] pseudo-cubic axis normal to the film surface is obtained. The average grain size decreases with decreasing film thickness t. The magnetic anisotropy depends upon the substrate-induced strain. Firstly, the intrinsic coercivity iHC increases as t varies from 5 nm to 10 nm, then attains a maximum at t～10—25nm. A further increase in t yields a gradual reduction of iHC. By the analysis of the dependence of iHC on the measured direction of magnetic field, the coercivity mechanism is assumed to be mainly determined by the nucleation of reversed domain and the domain wall pining for t≤10nm and t≥25nm, respectively, which were further verified by the investigation of the initial magnetization curves for the LCMO/STO films with t=5, 10, 25 and 400nm, and the minor magnetic loops for the LCMO/LAO films with t=5 and 50nm. Moreover, the size of the inhomogeneous region in which the nucleation or pinning takes place is discussed.

关键词: manganite film, thickness, magnetic anisotropy, coercivity

Abstract: We investigate the effects of strain and film thickness on the coercivity of La0.67Ca0.33MnO3 films grown on SrTiO3 and LaAlO3 substrates. Textured microstructure with the grain [001] pseudo-cubic axis normal to the film surface is obtained. The average grain size decreases with decreasing film thickness t. The magnetic anisotropy depends upon the substrate-induced strain. Firstly, the intrinsic coercivity iHC increases as t varies from 5 nm to 10 nm, then attains a maximum at t～10—25nm. A further increase in t yields a gradual reduction of iHC. By the analysis of the dependence of iHC on the measured direction of magnetic field, the coercivity mechanism is assumed to be mainly determined by the nucleation of reversed domain and the domain wall pining for t≤10nm and t≥25nm, respectively, which were further verified by the investigation of the initial magnetization curves for the LCMO/STO films with t=5, 10, 25 and 400nm, and the minor magnetic loops for the LCMO/LAO films with t=5 and 50nm. Moreover, the size of the inhomogeneous region in which the nucleation or pinning takes place is discussed.

Key words: manganite film, thickness, magnetic anisotropy, coercivity

中图分类号:  (Magnetic properties of monolayers and thin films)

  • 75.70.Ak
68.55.-a (Thin film structure and morphology) 75.60.Ej (Magnetization curves, hysteresis, Barkhausen and related effects) 75.30.Gw (Magnetic anisotropy) 75.60.Ch (Domain walls and domain structure) 68.55.A- (Nucleation and growth)