中国物理B ›› 2005, Vol. 14 ›› Issue (11): 2329-2334.doi: 10.1088/1009-1963/14/11/031

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Magnetoresistances and magnetic entropy changes associated with negative lattice expansions in NaZn13-type compounds LaFeCoSi

钱小陵1, 胡凤霞2, 高炬3, 王光军4, 孙继荣4, 沈保根4, 成昭华4   

  1. (1)Department of Physics, Capital Normal University, Beijing 100037, China; (2)Department of Physics, Capital Normal University, Beijing 100037, China;State Key Laboratory of Magnetism, Institute of Physics & Center of Condensed Matter Physics,Chinese Academy of Sciences, Beijing 100080, China;Department of Physics, The University o; (3)Department of Physics, The University of Hong Kong,Hong Kong, China; (4)State Key Laboratory of Magnetism, Institute of Physics & Center of Condensed Matter Physics,Chinese Academy of Sciences, Beijing 100080, China
  • 收稿日期:2005-01-12 修回日期:2005-07-03 出版日期:2005-11-20 发布日期:2005-11-20
  • 基金资助:
    Project supported by the State Key Development Program for Basic Research of China (Grant No 1998061303),the National Natural Science Foundation of China (Grant Nos 10474066 and 10174094), and the Beijing Natural Science Foundation of China (Grant No 101

Magnetoresistances and magnetic entropy changes associated with negative lattice expansions in NaZn13-type compounds LaFeCoSi

Hu Feng-Xia (胡凤霞)abc, Qian Xiao-Ling (钱小陵)a, Wang Guang-Jun (王光军)b, Sun Ji-Rong (孙继荣)b, Shen Bao-Gen (沈保根)b, Cheng Zhao-Hua (成昭华)b, Gao Ju (高炬)c   

  1. a Department of Physics, Capital Normal University, Beijing 100037, China; b State Key Laboratory of Magnetism, Institute of Physics & Center of Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080, Chinac Department of Physics, The University of Hong Kong, Hong Kong, China
  • Received:2005-01-12 Revised:2005-07-03 Online:2005-11-20 Published:2005-11-20
  • Supported by:
    Project supported by the State Key Development Program for Basic Research of China (Grant No 1998061303),the National Natural Science Foundation of China (Grant Nos 10474066 and 10174094), and the Beijing Natural Science Foundation of China (Grant No 101

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摘要： Magnetoresistances and magnetic entropy changes in NaZn13-type compounds La(Fe1-xCox)11.9Si1.1(x=0.04, 0.06, and 0.08) with Curie temperatures of 243\,K, 274\,K, and 301\,K, respectively, are studied. The ferromagnetic ordering is accompanied by a negative lattice expansion. Large magnetic entropy changes in a wide temperature range from \sim 230\,K to \sim 320\,K are achieved. Raising Co content increases the Curie temperature but weakens the gnetovolume effect, thereby causing a decrease in magnetic entropy change. These materials exhibit a metallic character below TC, whereas the electrical resistance decreases abruptly and then recovers the metal-like behaviour above TC. Application of a magnetic field retains the transitions via increasing the ferromagnetic ordering temperature. An isothermal increase in magnetic field leads to an increase in electrical resistance at temperatures near but above TC,which is a consequence of the field-induced metamagnetic transition from a paramagnetic state to a ferromagnetic state.

关键词: magnetoresistance, magnetic entropy change, negative lattice expansion, NaZn13-type compounds

Abstract: Magnetoresistances and magnetic entropy changes in NaZn13-type compounds La(Fe1-xCox)11.9Si1.1(x=0.04, 0.06, and 0.08) with Curie temperatures of 243 K, 274 K, and 301 K, respectively, are studied. The ferromagnetic ordering is accompanied by a negative lattice expansion. Large magnetic entropy changes in a wide temperature range from ~230 K to ~320 K are achieved. Raising Co content increases the Curie temperature but weakens the gnetovolume effect, thereby causing a decrease in magnetic entropy change. These materials exhibit a metallic character below TC, whereas the electrical resistance decreases abruptly and then recovers the metal-like behaviour above TC. Application of a magnetic field retains the transitions via increasing the ferromagnetic ordering temperature. An isothermal increase in magnetic field leads to an increase in electrical resistance at temperatures near but above TC, which is a consequence of the field-induced metamagnetic transition from a paramagnetic state to a ferromagnetic state.

Key words: magnetoresistance, magnetic entropy change, negative lattice expansion, NaZn13-type compounds

中图分类号:  (Metals and alloys)

  • 75.47.Np
75.30.Sg (Magnetocaloric effect, magnetic cooling) 75.50.Bb (Fe and its alloys) 75.30.Kz (Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)) 75.80.+q (Magnetomechanical effects, magnetostriction)