摘要
Magnetic properties and magnetocaloric effects （MCEs） of the HoPdA1 compounds with the hexagonal ZrNiAl-type and the orthorhombic TiNiSi-type structures are investigated. Both the compounds are found to be antiferromagnet with the Nrel tem- perature TN=12 and 10 K, respectively. A field-induced metamagnetic transition from antiferromagnetic （AFM） state to ferro- magnetic （FM） state is observed below TN. For the hexagonal HoPdA1, a small magnetic field can induce an FM-like state due to a weak AFM coupling, which leads to a high saturation magnetization and gives rise to a large MCE around TN. The maxi- mal value of magnetic entropy change （ASM） is -20.6 J/kg K with a refrigerant capacity （RC） value of 386 J/kg for a field change of 0-5 T. For the orthorhombic HoPdA1, the critical field required for metamagnetic transition is estimated to be about 1.5 T, showing a strong AFM coupling. However, the maximal ASM value is still -13.7 J/kg K around TN for a field change of 0-5 T. The large reversible ASM and considerable RC suggest that HoPdA1 may be an appropriate candidate for magnetic re- frigerant in a low temperature range.
基金
supported by the National Natural Science Foundation of China (Grant Nos. 50731007 and 51021061)
the Knowledge Innovation Project of the Chinese Academy of Sciences
the High-Technology Research and Development Program of China
