中国物理B ›› 2013, Vol. 22 ›› Issue (10): 107502-107502.doi: 10.1088/1674-1056/22/10/107502

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Transformation behaviors, structural and magnetic characteristics of Ni–Mn–Ga films on MgO (001)

谢忍, 唐少龙, 唐妍梅, 刘枭辰, 唐涛, 都有为   

  1. National Laboratory of Microstructures, Jiangsu Provincial Laboratory for Nanotechnology and Department of Physics, Nanjing University, Nanjing 210093, China
  • 收稿日期:2013-05-14 修回日期:2013-06-07 出版日期:2013-08-30 发布日期:2013-08-30
  • 基金资助:
    Project supported by the National Key Project of Fundamental Research of China (Grant No. 2012CB932304), the National Natural Science Foundation of China (Grant No. 50831006), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

Transformation behaviors, structural and magnetic characteristics of Ni–Mn–Ga films on MgO (001)

Xie Ren (谢忍), Tang Shao-Long (唐少龙), Tang Yan-Mei (唐妍梅), Liu Xiao-Chen (刘枭辰), Tang Tao (唐涛), Du You-Wei (都有为)   

  1. National Laboratory of Microstructures, Jiangsu Provincial Laboratory for Nanotechnology and Department of Physics, Nanjing University, Nanjing 210093, China
  • Received:2013-05-14 Revised:2013-06-07 Online:2013-08-30 Published:2013-08-30
  • Contact: Tang Shao-Long E-mail:tangsl@nju.edu.cn
  • Supported by:
    Project supported by the National Key Project of Fundamental Research of China (Grant No. 2012CB932304), the National Natural Science Foundation of China (Grant No. 50831006), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

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摘要： Ferromagnetic Ni-Mn-Ga films were fabricated by depositing on MgO (001) substrates at temperatures from 673 K to 923 K. Microstructure, crystal structure, martensitic transformation behavior, and magnetic properties of the films were studied. With increasing deposition temperature, the surface morphology of the films transforms from granular to continuous. The martensitic transformation temperature is not dependent on deposition temperature; while transformation behavior is affected substantially by deposition temperature. X-ray analysis reveals that the film deposited at 873 K has a 7M martensite phase, and its magnetization curve provides a typical step-increase, indicating the occurrence of magnetically induced reorientation (MIR). In situ magnetic domain structure observation on the film deposited at 873 K reflects that the martensitic transformation could be divided into two periods: nucleation and growth, in the form of stripe domains. The MIR occurs at the temperature at which martensitic transformation starts, and the switching field increases with the decrease of temperature due to damped thermal activation. The magnetically induced martensitic transformation is related to the difference of magnetization between martensite and austenite. A shift of martensite temperature of dT/dH=0.43 K/T is observed, consistent with the theoretical value, 0.41 K/T.

关键词: Ni-Mn-Ga film, ferromagnetic-shape memory alloy, transformation behavior, magnetically induced reorientation, magnetically induced martensitic transformation

Abstract: Ferromagnetic Ni–Mn–Ga films were fabricated by depositing on MgO (001) substrates at temperatures from 673 K to 923 K. Microstructure, crystal structure, martensitic transformation behavior, and magnetic properties of the films were studied. With increasing deposition temperature, the surface morphology of the films transforms from granular to continuous. The martensitic transformation temperature is not dependent on deposition temperature; while transformation behavior is affected substantially by deposition temperature. X-ray analysis reveals that the film deposited at 873 K has a 7M martensite phase, and its magnetization curve provides a typical step-increase, indicating the occurrence of magnetically induced reorientation (MIR). In situ magnetic domain structure observation on the film deposited at 873 K reflects that the martensitic transformation could be divided into two periods: nucleation and growth, in the form of stripe domains. The MIR occurs at the temperature at which martensitic transformation starts, and the switching field increases with the decrease of temperature due to damped thermal activation. The magnetically induced martensitic transformation is related to the difference of magnetization between martensite and austenite. A shift of martensite temperature of dT/dH=0.43 K/T is observed, consistent with the theoretical value, 0.41 K/T.

Key words: Ni–Mn–Ga film, ferromagnetic-shape memory alloy, transformation behavior, magnetically induced reorientation, magnetically induced martensitic transformation

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

  • 75.70.Ak
75.70.Kw (Domain structure (including magnetic bubbles and vortices))