中国物理B ›› 2008, Vol. 17 ›› Issue (8): 3087-3092.doi: 10.1088/1674-1056/17/8/053

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Magnetic properties and magnetocaloric effect in NdxLa1-xFe11.5Al1.5 compounds

王 芳, 王光军, 孙继荣, 沈保根   

  1. State Key Laboratory of Magnetism, Institute of Physics and Centre for Condensed Matter Physics, \Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2007-11-06 修回日期:2008-03-24 出版日期:2008-08-20 发布日期:2008-08-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos 50571112 and 50731007), the National Basic Research Program of China (Grant No 2006CB601101) and the Basic Research Program of Chinese Academy of Science (Grant No KJCX2-YW-W02s).

Magnetic properties and magnetocaloric effect in NdxLa1-xFe11.5Al1.5 compounds

Wang Fang(王芳)†, Wang Guang-Jun(王光军), Sun Ji-Rong(孙继荣), and Shen Bao-Gen(沈保根)   

  1. State Key Laboratory of Magnetism, Institute of Physics and Centre for Condensed Matter Physics,  Chinese Academy of Sciences, Beijing 100190, China
  • Received:2007-11-06 Revised:2008-03-24 Online:2008-08-20 Published:2008-08-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos 50571112 and 50731007), the National Basic Research Program of China (Grant No 2006CB601101) and the Basic Research Program of Chinese Academy of Science (Grant No KJCX2-YW-W02s).

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摘要： Effects of Nd-doping on the magnetic properties and magnetocaloric effects (MCEs) of Nd$_{x}$La$_{1 - x}$Fe$_{11.5}$Al$_{1.5}$ have been investigated. Substitution of Nd leads to a weakening of the antiferromagnetic (AFM) coupling and an enhancement of the ferromagnetic (FM) coupling. This in turn results in a complex magnetic behaviour for Nd$_{0.2}$La$_{0.8}$Fe$_{11.5}$Al$_{1.5}$ characterized by the occurrence of two phase transitions at $\sim$188\,K (PM--AFM) and $\sim $159\,K (AFM--FM). As a result, a table-like MCE (9\,J/kg$\cdot$K) is found in a wide temperature range (160--185\,K) for a field change of 0--5\,T around the transition temperature, as evidenced by both the magnetic and calorimetric measurements. Based on the analysis of low-temperature heat capacity, it is found that the AFM--FM phase transition modifies the electron density significantly, and the major contribution to the entropy change comes from the electronic entropy change.

关键词: magnetic properties, NaZn$_{13}$-type compounds, magnetic entropy change

Abstract: Effects of Nd-doping on the magnetic properties and magnetocaloric effects (MCEs) of Nd$_{x}$La$_{1 - x}$Fe$_{11.5}$Al$_{1.5}$ have been investigated. Substitution of Nd leads to a weakening of the antiferromagnetic (AFM) coupling and an enhancement of the ferromagnetic (FM) coupling. This in turn results in a complex magnetic behaviour for Nd$_{0.2}$La$_{0.8}$Fe$_{11.5}$Al$_{1.5}$ characterized by the occurrence of two phase transitions at $\sim$188 K (PM--AFM) and $\sim $159 K (AFM--FM). As a result, a table-like MCE (9 J/kg$\cdot$K) is found in a wide temperature range (160--185 K) for a field change of 0--5 T around the transition temperature, as evidenced by both the magnetic and calorimetric measurements. Based on the analysis of low-temperature heat capacity, it is found that the AFM--FM phase transition modifies the electron density significantly, and the major contribution to the entropy change comes from the electronic entropy change.

Key words: magnetic properties, NaZn$_{13}$-type compounds, magnetic entropy change

中图分类号:  (Magnetocaloric effect, magnetic cooling)

  • 75.30.Sg
75.30.Kz (Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)) 75.40.Cx (Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)) 75.50.Bb (Fe and its alloys) 75.50.Ee (Antiferromagnetics) 75.60.Ej (Magnetization curves, hysteresis, Barkhausen and related effects)