Magnetic entropy change involving martensitic transition in NiMn-based Heusler alloys

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	Magnetic entropy change involving martensitic transition in NiMn-based Heusler alloys
	Hu, FX ; Shen, BG ; Sun, JR
刊名	CHINESE PHYSICS B
	2013
卷号	22 期号:3
关键词	magnetic entropy change martensitic transition NiMn-based Heusler alloys
ISSN号	1674-1056
通讯作者	Hu, FX (reprint author), Chinese Acad Sci, Inst Phys, State Key Lab Magnetism, Beijing 100190, Peoples R China.
中文摘要	Our recent progress on magnetic entropy change (Delta S) involving martensitic transition in both conventional and metamagnetic NiMn-based Heusler alloys is reviewed. For the conventional alloys, where both martensite and austenite exhibit ferromagnetic (FM) behavior but show differentmagnetic anisotropies, a positive Delta S as large as 4.1 J.kg(-1).K-1 under a field change of 0-0.9 T was first observed at martensitic transition temperature T-M similar to 197 K. Through adjusting the Ni:Mn:Ga ratio to affect valence electron concentration e/a, T-M was successfully tuned to room temperature, and a large negative Delta S was observed in a single crystal. The -Delta S attained 18.0 J.kg(-1).K-1 under a field change of 0-5 T. We also focused on the metamagnetic alloys that show mechanisms different from the conventional ones. It was found that post-annealing in suitable conditions or introducing interstitial H atoms can shift the T-M across a wide temperature range while retaining the strong metamagnetic behavior, and hence, retaining large magnetocaloric effect (MCE) and magnetoresistance (MR). The melt-spun technique can disorder atoms and make the ribbons display a B2 structure, but the metamagnetic behavior, as well as the MCE, becomes weak due to the enhanced saturated magnetization of martensites. We also studied the effect of Fe/Co co-doping in Ni-45(Co1-xFex)(5)Mn36.6In13.4 metamagnetic alloys. Introduction of Fe atoms can assist the conversion of the Mn-Mn coupling from antiferromagnetic to ferromagnetic, thus maintaining the strong metamagnetic behavior and large MCE and MR. Furthermore, a small thermal hysteresis but significant magnetic hysteresis was observed around T-M in Ni51Mn49-xInx metamagnetic systems, which must be related to different nucleation mechanisms of structural transition under different external perturbations.
资助信息	National Natural Science Foundation of China [51271196, 11274357, 51021061]; Key Research Program of the Chinese Academy of Sciences; National Basic Research Program of China [2010CB833102]; Hi-Tech Research and Development Program of China [2011AA03A404]
语种	英语
公开日期	2014-01-16
内容类型	期刊论文
源URL	[http://ir.iphy.ac.cn/handle/311004/57187]
专题	物理研究所_物理所公开发表论文_物理所公开发表论文_期刊论文
推荐引用方式 GB/T 7714	Hu, FX,Shen, BG,Sun, JR. Magnetic entropy change involving martensitic transition in NiMn-based Heusler alloys[J]. CHINESE PHYSICS B,2013,22(3).
APA	Hu, FX,Shen, BG,&Sun, JR.(2013).Magnetic entropy change involving martensitic transition in NiMn-based Heusler alloys.CHINESE PHYSICS B,22(3).
MLA	Hu, FX,et al."Magnetic entropy change involving martensitic transition in NiMn-based Heusler alloys".CHINESE PHYSICS B 22.3(2013).