| Magnetoresistances and magnetic entropy changes associated with negative lattice expansions in NaZn13-type compounds LaFeCoSi |
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| 作者姓名： | 胡凤霞 钱小陵 王光军 孙继荣 沈保根 成昭华 高炬 |
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| 作者单位： | 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 of Hong Kong,Hong Kong, China;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;State Key Laboratory of Magnetism, Institute of Physics & Center of Condensed Matter Physics,Chinese Academy of Sciences, Beijing 100080, China;State Key Laboratory of Magnetism, Institute of Physics & Center of Condensed Matter Physics,Chinese Academy of Sciences, Beijing 100080, 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 of Hong Kong,Hong Kong, China |
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| 基金项目： | 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 1012002). |
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| 摘 要： | Magnetoresistances and magnetic entropy changes in NaZn13-type compounds La（Fel-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 magnetovolume 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.
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| 关 键 词： | 磁阻效应 磁熵变化 NaZn13化合物 居里温度 铁磁体 负格子扩展 |
| 收稿时间： | 2005-03-12 |
| 修稿时间： | 7/3/2005 12:00:00 AM |
Magnetoresistances and magnetic entropy changes associated with negative lattice expansions in NaZn13-type compounds LaFeCoSi |
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| Hu Feng-Xi,Qian Xiao-Ling,Wang Guang-Jun,Sun Ji-Rong,Shen Bao-Gen,Cheng Zhao-Hua and Gao Ju.Magnetoresistances and magnetic entropy changes associated with negative lattice expansions in NaZn13-type compounds LaFeCoSi[J].Chinese Physics B,2005,14(11):2329-2334. |
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| Authors: | Hu Feng-Xi Qian Xiao-Ling Wang Guang-Jun Sun Ji-Rong Shen Bao-Gen Cheng Zhao-Hua and Gao Ju |
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| 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 \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. |
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| Keywords: | magnetoresistance magnetic entropy change negative lattice expansion NaZn13-type compounds |
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