中文摘要：

NaZn13型La（Fe,Si）13化合物随Si含量增加,相变性质由一级过渡为二级,化合物晶胞体积收缩,饱和磁化强度降低,居里温度升高。其居里温度与晶胞体积之间的关系不能用Bethe-Slater曲线给出合理的解释。本文利用添加间隙原子碳调节La（Fe,Si）13化合物晶胞体积和居里温度的方法,系统研究了该化合物居里温度与晶胞体积之间的关系。结果发现二者之间的变化规律遵循Jaccarino-Walker模型,即仅有5%甚至更少的3d电子被认为是真正的巡游电子,其余的3d电子仍是局域的。以极化的巡游电子为媒介,局域电子之间产生类似于Ruderman-Kittel-Kasuya-Yosida 的长程相互作用,相互作用的符号和大小与距离呈周期性震荡。随Si含量的增加, La（Fe,Si）13化合物巡游电子数目增加,化合物的居里温度由晶胞体积和巡游电子的浓度共同决定。

英文摘要：

In NaZn13 type La（Fe,Si）13 compound, the phase transition nature varies from the first order to the second order, the cell volume contracts, the saturated magnetization decreases and the Curie temperature increases with increasing Si content. In this paper, the relation between the Curie temperature and the cell volume is investigated systematically by introducing the interstitial carbon atoms, which is an efficient method to control the cell volume and the Curie temperature. It is found that the relation between the Curie temperature and the cell volume is consistent with the Jaccarino-Walker model, in which only 5% or less 3d electrons are considered as the itinerant electrons and the others are regarded as the localized ones. With the polarized itinerant electrons used as a medium, the interaction between the 3d localized electrons is similar to Ruderman-Kittel-Kasuya-Yosida interaction, whose sign and magnitude oscillate periodically with distance. The number of the itinerant electrons of the La （Fe,Si）13 increases with the increase of Si content. The Curie temperature is dependent on both the cell volume and the number of itinerant electrons.