Abstract We studied the influence of La (nonmagnetic) and Ce (intermediate valence) impurities on the ferromagnetic ordering temperature Tc of compounds RE1-x(La,Ce)xNi (RE = Pr, Gd). The ordering temperature Tc was measured in a wide range of impurity concentration. Crystal electric field (CEF) splitting for the PrNi and Pr0.25Ce0.75Ni was defined by neutron spectroscopy measurements. The strong difference in the influence of La and Ce on Tc of PrNi and GdNi based systems has been obtained. The introduction of a spin-fluctuating intermediate valence impurity in PrNi leads to a dramatic increase in the area of the ordered state on the phase diagram, due to an increase in Tc, compared to the impact of La-impurity over the entire concentration range. The dependence of Tc on the Ce concentration for the Pr1-xCexNi was calculated within the framework of the model of microscopic states. The essential modification of the CEF splitting by the Ce impurity appears to be the decisive factor affecting Tc wherein the Ce ion carries zero static magnetic moments similar to the La case. The latter explains the identical dependencies of the ordering temperature on the impurity concentration observed in systems with a long-range order of local magnetic moments Gd1-xLaxNi and Gd1-xCexNi.

中文翻译：

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中间价杂质对单线态基态系统 PrNi 中感应磁性的显着影响

摘要 我们研究了 La（非磁性）和 Ce（中间价）杂质对化合物 RE1-x(La,Ce)xNi (RE = Pr, Gd) 铁磁有序温度 Tc 的影响。在较宽的杂质浓度范围内测量有序温度 Tc。PrNi 和 Pr0.25Ce0.75Ni 的晶体电场 (CEF) 分裂由中子能谱测量定义。已经获得了 La 和 Ce 对 PrNi 和 GdNi 基系统 Tc 的影响的强烈差异。与 La 杂质在整个浓度范围内的影响相比，由于 Tc 的增加，在 PrNi 中引入自旋波动的中间价杂质导致相图上有序状态的面积急剧增加。在微观状态模型的框架内计算了 Tc 对 Pr1-xCexNi 的 Ce 浓度的依赖性。Ce 杂质对 CEF 分裂的基本修改似乎是影响 Tc 的决定性因素，其中 Ce 离子携带与 La 情况类似的零静磁矩。后者解释了在具有长程局部磁矩 Gd1-xLaxNi 和 Gd1-xCexNi 有序的系统中观察到的有序温度对杂质浓度的相同依赖性。