(1. 上海电力学院 物理系，上海 200090；
2. 上海市高温超导重点实验室，上海大学，上海 200444)
摘 要: 采用真空电弧炉熔炼法制备MnCo0.95Cu0.05Ge合金，并分别利用X射线衍射和物性测量系统研究了其结构、磁性和磁热效应。室温下的X射线衍射数据表明，样品呈现六角(Ni2In型)单相结构；随着温度降低，样品发生顺磁-铁磁二级相变，其居里温度TC约为257 K。TC以下样品呈现强铁磁性，这主要是由次晶格Mn-Mn原子间的交换作用引起的。在TC附近，合金样品显示了巨大的磁热效应；当外加磁场变化为2、5和7 T时，最大磁熵变分别达到了4.49、10.19和13.64 J/(kg？K)，相对应的制冷量分别为103.27、249.66和347.82 J/kg。
关键字: MnCoGe合金；磁热效应；铁磁性能；磁化曲线
（1. Department of Physics, Shanghai University of Electric Power, Shanghai 200090, China;
2. Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University, Shanghai 200444, China）
Abstract:The structure, magnetic and magnetocaloric properties of MnCo0.95Cu0.05Ge alloy prepared by arc melting method were studied. X-ray diffraction data at room temperature indicate that the sample exists a single phase of Ni2In-type hexagonal structure. It shows strong ferromagnetic properties below the Curie temperature (TC) about 257 K. With the increase of temperature, a reversible second order phase transition from ferromagnetic to paramagnetic state is observed at TC, accompanied with a large magnetocaloric effect, which is mainly due to the exchange effect of Mn-Mn ordering. The maximum magnetic entropy changes are 4.49, 10.19 and 13.64 J/(kg？K) at applied magnetic field of 2, 5 and 7 T, the corresponding relative cooling power are calculated to be 103.27, 249.66 and 347.82 J/kg, respectively.
Key words: MnCoGe alloy; magnetocaloric effect; ferromagnetic order system; magnetic curves
