›› 2014, Vol. 23 ›› Issue (8): 87503-087503.doi: 10.1088/1674-1056/23/8/087503

• SPECIAL TOPI—International Conference on Nanoscience & Technology, China 2013 • 上一篇    下一篇

Large coercivity and unconventional exchange coupling in manganese-oxide-coated manganese–gallium nanoparticles

冯俊宁, 刘伟, 耿殿禹, 马嵩, 余涛, 赵晓天, 代志明, 赵新国, 张志东   

  1. Shenyang National Laboratory for Materials Science and International Center for Materials Physics, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
  • 收稿日期:2013-09-04 修回日期:2014-03-20 出版日期:2014-08-15 发布日期:2014-08-15
  • 基金资助:
    Projected supported by the National Basic Research Program of China (Grant No. 2010CB934603), the National High Technology Research and Development Program of China (863 Program) (Grant No. 2011AA03A402), and the National Natural Science Foundation of China (Grant Nos. 50931006, 51271177, and 51271179).

Large coercivity and unconventional exchange coupling in manganese-oxide-coated manganese–gallium nanoparticles

Feng Jun-Ning (冯俊宁), Liu Wei (刘伟), Geng Dian-Yu (耿殿禹), Ma Song (马嵩), Yu Tao (余涛), Zhao Xiao-Tian (赵晓天), Dai Zhi-Ming (代志明), Zhao Xin-Guo (赵新国), Zhang Zhi-Dong (张志东)   

  1. Shenyang National Laboratory for Materials Science and International Center for Materials Physics, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
  • Received:2013-09-04 Revised:2014-03-20 Online:2014-08-15 Published:2014-08-15
  • Contact: Liu Wei E-mail:wliu@imr.ac.cn
  • Supported by:
    Projected supported by the National Basic Research Program of China (Grant No. 2010CB934603), the National High Technology Research and Development Program of China (863 Program) (Grant No. 2011AA03A402), and the National Natural Science Foundation of China (Grant Nos. 50931006, 51271177, and 51271179).

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摘要： The microstructures and magnetic properties of nanoparticles, each composed of an antiferromagnetic (AFM) manganese-oxide shell and a ferromagnetic-like core of manganese-gallium (MnGa) compounds, are studied. The core-shell structure is confirmed by transmission electron microscope (TEM). The ferromagnetic-like core contains three kinds of MnGa binary compounds, i.e., ferrimagnetic (FI) D022-type Mn3Ga, ferromagnetic (FM) Mn8Ga5, and AFM D019-type Mn3Ga, of which the first two correspond respectively to a hard magnetic phase and to a soft one. Decoupling effect between these two phases is found at 1ow temperature, which weakens gradually with increasing temperature and disappears above 200 K. The exchange bias (EB) effect is observed simultaneously, which is caused by the exchange coupling between the AFM shell and FM-like core. A large coercivity of 6.96 kOe (1 Oe = 79.5775 A·m-1) and a maximum EB value of 0.45 kOe are achieved at 300 K and 200 K respectively.

关键词: nanoparticle, core-shell structure, exchange coupling

Abstract: The microstructures and magnetic properties of nanoparticles, each composed of an antiferromagnetic (AFM) manganese-oxide shell and a ferromagnetic-like core of manganese-gallium (MnGa) compounds, are studied. The core-shell structure is confirmed by transmission electron microscope (TEM). The ferromagnetic-like core contains three kinds of MnGa binary compounds, i.e., ferrimagnetic (FI) D022-type Mn3Ga, ferromagnetic (FM) Mn8Ga5, and AFM D019-type Mn3Ga, of which the first two correspond respectively to a hard magnetic phase and to a soft one. Decoupling effect between these two phases is found at 1ow temperature, which weakens gradually with increasing temperature and disappears above 200 K. The exchange bias (EB) effect is observed simultaneously, which is caused by the exchange coupling between the AFM shell and FM-like core. A large coercivity of 6.96 kOe (1 Oe = 79.5775 A·m-1) and a maximum EB value of 0.45 kOe are achieved at 300 K and 200 K respectively.

Key words: nanoparticle, core-shell structure, exchange coupling

中图分类号:  (Magnetic properties of nanostructures)

  • 75.75.-c
71.70.Gm (Exchange interactions)