Abstract In this work we report on the structural, magnetic and magnetocaloric properties of polycrystalline HoNi 2 and ErNi 2 Laves-phase compounds. Powder X-ray diffraction studies at room temperature show that the compounds crystallize in the cubic C15 structure (MgCu 2 type). The magnetic measurements reveal that the second-order magnetic phase transition from ferromagnetic to paramagnetic state appears at T C equal 13.5 K for HoNi 2 and 6.5 K for ErNi 2 . Using direct measurements over a wide field range (up to 11 T), along with indirect methods, we have found low and high field regularities of the magnetocaloric effect characterized by the adiabatic temperature change, ΔT ad , and the isothermal magnetic entropy change, ΔS mag . The magnetocaloric properties near the phase transition are discussed in the framework of the Landau theory for the second-order phase transitions.

中文翻译：

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HoNi 2 和 ErNi 2 化合物在低温下有序的结构、磁性和磁热性能

摘要 在这项工作中，我们报告了多晶 HoNi 2 和 ErNi 2 Laves 相化合物的结构、磁性和磁热特性。室温下的粉末 X 射线衍射研究表明化合物以立方 C15 结构（MgCu 2 型）结晶。磁性测量表明，从铁磁态到顺磁态的二阶磁相变出现在 TC 等于 13.5 K 的 HoNi 2 和 6.5 K 的 ErNi 2 。使用在宽场范围（高达 11 T）上的直接测量以及间接方法，我们发现了以绝热温度变化 ΔT ad 和等温磁熵变化 ΔS 为特征的磁热效应的低场和高场规律杂志