六度轴对称Fe_8原子簇的电子结构和磁性质

Electronic Structure and Magnetism of Fe_8-cluster With Sixfold Axis

用自旋极化的ＭＳ－Ｘα方法计算了Ｎｄ２Ｆｅ１７化合物中含哑铃Ｆｅ原子对的Ｆｅ８原子簇的电子结构和磁矩。计算结果显示，在Ｆｅ（ｃ）和Ｆｅ（ｆ）间的分子轨道中，有三个奇宇称轨道呈现负交换耦合。通过比较α－Ｆｅ的ＭＳ－Ｘα计算结果，能够很好地说明Ｎｄ２Ｆｅ１７化合物居里温度较低的原因。对Ｒ２Ｆｅ１７型化合物中影响Ｆｅ－Ｆｅ交换作用大小的主要因素，本文也作了讨论。

Electronic structure of the Fe8 cluster taken from the Nd2Fe17 compound has been calculated with spin-polarized MS-Xα method.The calculation showed that there are negative exchange couplings occurring at three hybridized orbitals of odd parity between Fe(f) and Fe(c) atoms.Based on the structural and magnetic characteristics of the cluster,the low curie temperature of the Nd2Fe17 compound could be explained. The key factors controlling the curie temperatures of R2Fe17 compounds were discussed.