(1. 上海電力學(xué)院 物理系，上海 200090；
2. 上海市高溫超導(dǎo)重點實驗室，上海大學(xué)，上海 200444)
摘 要: 采用真空電弧爐熔煉法制備MnCo0.95Cu0.05Ge合金，并分別利用X射線衍射和物性測量系統(tǒng)研究了其結(jié)構(gòu)、磁性和磁熱效應(yīng)。室溫下的X射線衍射數(shù)據(jù)表明，樣品呈現(xiàn)六角(Ni2In型)單相結(jié)構(gòu)；隨著溫度降低，樣品發(fā)生順磁-鐵磁二級相變，其居里溫度TC約為257 K。TC以下樣品呈現(xiàn)強鐵磁性，這主要是由次晶格Mn-Mn原子間的交換作用引起的。在TC附近，合金樣品顯示了巨大的磁熱效應(yīng)；當(dāng)外加磁場變化為2、5和7 T時，最大磁熵變分別達(dá)到了4.49、10.19和13.64 J/(kg？K)，相對應(yīng)的制冷量分別為103.27、249.66和347.82 J/kg。
關(guān)鍵字: MnCoGe合金；磁熱效應(yīng)；鐵磁性能；磁化曲線
（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
