Determination of the entropy changes in the compounds with a first-order magnetic transition

被引：244
作者：
Liu, G. J.
Sun, J. R.
Shen, J.
Gao, B.
Zhang, H. W.
Hu, F. X.
Shen, B. G.
机构：
[1] Chinese Acad Sci, Inst Phys, State Key Lab Magnetism, Beijing 100080, Peoples R China
[2] Chinese Acad Sci, Ctr Condensed Matter Phys, Beijing 100080, Peoples R China
[3] Hebei Univ Technol, Sch Mat Sci & Engn, Tianjin 300130, Peoples R China
来源：
APPLIED PHYSICS LETTERS | 2007年 / 90卷 / 03期
基金：
中国国家自然科学基金;
关键词：
Lanthanum compounds;
D O I：
10.1063/1.2425033
中图分类号：
O59 [应用物理学];
学科分类号：
摘要：
Entropy changes in the compounds of La1-xPrxFe11.5Si1.5 (x=0.3 and 0.4) have been experimentally studied. A tower-shaped entropy change of the height of similar to 27 J/kg K is obtained based on the analyses of heat capacity, while the Maxwell relation predicts an extra entropy peak of the height of similar to 99 J/kg K, slightly varying with Pr content. A careful study indicates that the Maxwell relation cannot be used in the vicinity of the Curie temperature because of the coexistence of paramagnetic and ferromagnetic phases, and the huge entropy peak is a spurious result. Similar conclusions are applicable to MnAs and Mn1-xFexAs, for which huge entropy changes have been reported. Appropriate methods for the determination of entropy change of the compound with phase separation are discussed based on the magnetic data. (c) 2007 American Institute of Physics.
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页数：3
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