一级磁结构相变材料Mn_(0.6)Fe_(0.4)NiSi_(0.5)Ge_(0.5)和Ni_(50)Mn_(34)Co_2Sn_(14)的磁热效应与磁场的线性相关性  

Linear dependence of magnetocaloric effect on magnetic field in Mn_(0.6)Fe_(0.4)NiSi_(0.5)Ge_(0.5)and Ni_(50)Mn_(34)Co_2Sn_(14) with first-order magnetostructural transformation

作　　者：张虎[1] 邢成芬 龙克文 肖亚宁 陶坤 王利晨 龙毅[1] Zhang Hu;Xing Cheng-Fen;Long Ke-Wen;Xiao Ya-Ning;Tao Kun;Wang Li-Chen;Long Yi(School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China;Chengxian Technology Co.Ltd.,Foshan 528513,China;Chuandong Magnetic Electronic Co.Ltd.,Foshan 528513,China;Department of Physics,Capital Normal University,Beijing 100048,China)

机构地区：[1]北京科技大学材料科学与工程学院,北京100083 [2]佛山市程显科技有限公司,佛山528513 [3]佛山市川东磁电股份有限公司,佛山528513 [4]首都师范大学物理系,北京100048

出　　处：《物理学报》2018年第20期458-464,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51671022;51701130);国家重点研发计划(批准号:2017YFB0702704);北京市自然科学基金(批准号:2162022);佛山市科技计划(批准号:2015IT100044)资助的课题~~

摘　　要：磁熵变(ΔS_M)与磁场(μ_0H)的相关性已在很多二级相变材料中被研究并报道,但一级相变材料的磁热效应与磁场相关性还少有报道.本文在具有一级磁结构相变的Mn_(0.6)Fe_(0.4)NiSi_(0.5)Ge_(0.5)材料中研究发现△S_M与μ_0H存在线性相关性,并通过麦克斯韦关系式的数值分析详细讨论了这一线性相关性的来源.同时,进一步发现在低磁场时,△S_M近似正比于μ_0H的平方.该线性相关性同样在一级磁结构相变Ni_(50)Mn_(34)Co_2Sn_(14)材料中得到了印证.但由于一级磁弹相变LaFe_(11.7)Si_(1.3)材料相变温度具有更强的磁场依赖性,不具有△S_M的线性相关性,因此,本研究表明,当磁结构相变材料的相变温度具有弱磁场依赖性时,ΔS_M与μ_0H具有线性相关性.进而,在磁场未达到相变饱和磁场以下,利用ΔS_M与μ_0H的线性相关性可以有效推测更高磁场下的△S_M.The study on the field dependence of magnetocaloric effect（MCE） is considered to be of fundamental and practical importance, since it not only guides us in understanding and optimizing the MCE, but also helps us estimate the MCE for higher magnetic field which is not available in some laboratories. The magnetic field（μ0 H） dependence of magnetic entropy change（ΔSM） has been studied extensively in many materials with second-order magnetic transition. However,the field dependence of MCE for first-order magnetic transition（FOMT） materials has not been sufficiently studied due to their complexity and diversity. In the present work, polycrystalline Mn（0.6）Fe（0.4）NiSi（0.5）Ge（0.5）, Ni（50）Mn（34）Co2 Sn（14）, and LaFe（11.7）Si（1.3） compounds with FOMT are prepared, and the magnetic and magnetocaloric properties are investigated systematically. In order to avoid a spurious ΔSM, the M-μ0 H curves are measured in a loop process. The M-μ0 H curves are corrected by taking into account the demagnetization effect, i.e. H（int） = H（ext）-NdM. It is found that the-ΔSM follows a linear relationship-ΔSM =-ΔS0＋κμ0 H with the variation of magnetic field in Mn（0.6）Fe（0.4）NiSi（0.5）Ge（0.5）compound when μ0 H 1 T. In addition, it is also noted that the △SM is approximately proportional to the square of μ0 H at low field. The origin of this linear relationship between △SM and μ0 H at high field and the deviation at low field are discussed by numerically analyzing the Maxwell relation. In addition to the ΔSM peak value, it is found that other ΔSM values at different temperatures also follow the linear relation at high field by performing the same numerical analysis. Moreover, it is found that the fitted ΔSM curve matches the experimental data very well. This result indicates that the linear relationship between ASm and μ0 H could be utilized to predict the ΔSM for higher magnetic field change when the field is lower than the saturation field. The a

关 键 词：磁热效应 磁熵变 磁结构相变 

分 类 号：TB34[一般工业技术—材料科学与工程]