摘要
用自旋极化的MS—Xα方法研究了原子簇Sm5Co28Si6的电子态密度、自旋能级劈裂及原子磁矩。结果显示，由于Sm—Co间的轨道杂化效应，使Sm原子的5d^0空轨道上占据了少量5d电子。Co（3d）-Sm（5d）电子间的直接交换作用，构成Sm—Co间的主要耦合方式，这是化合物SmCo5.85Si0．90中形成铁磁性长程序的一个重要因素。Si的掺杂使2e晶位的负交换耦合作用明显减弱，Fermi面处电子间键合作用增强，化合物的系统自由能降低，从而有利于形成稳定的铁磁性结构。考虑到深层4f电子的局域性以及轨道杂化效应所产生的少量5d电子，可以得到Sm的原子磁矩为1．24μB，与顺磁盐中Sm^3＋的磁矩实验值（1．32～1．63μB）基本符合。
Electronic structures of Sm5 Co28 Si6 cluster were studied by using spin - polarized MS - Xα method. The results show that a few of electrons are transferred to Sm（5d^0） orbit because of orbital hybridization between Sm and Co atoms. The exchange interactions between 3d and 5d electrons lead to the magnetic coupling between Sm and Co, and that results in the long - range ferromagnetic order in SmCo5.85Si0.90. The calculated results for the cluster reveal that SmCo5.85Si0.90 is stable phase. Since the spin - up DOS peak of d electrons at EF rises and the bonding of electrons at EF strengthens with increasing Si concentration, the free energy of alloys decreases and the stable ferromagnetic order forms in SmCo5.85Si0.90. Considering the localization of 4f electrons and a few of 5d electrons, the magnetic moment of Sm will be 1.24μB which is in agreement with the experiments of Sm^3＋ ion -moment in metals （1.32 - 1.63μB）.
出处
《功能材料与器件学报》
EI
CAS
CSCD
北大核心
2006年第1期35-39,共5页
Journal of Functional Materials and Devices
基金
国家高技术研究发展计划项目(No.2002AA324050)
山东省自然科学基金(No.Y2002D9Y2004A10)
关键词
电子结构
自旋极化
原子磁矩
交换耦合
electronic structure
spin polarization
atomic magnetic moment
exchange coupling
