化合物SmCo5的电子结构、自旋和轨道磁矩及其交换作用分析

用自旋极化的MS-Xα方法研究了稀土-过渡族化合物SmCo5₅的电子态密度、自 旋能级劈裂及原子磁矩.研究结果显示，由于化合物中Sm-Co间的轨道杂化效应，使Sm原子原来的5d00空轨道上占据了少量5d电子.由于Co(3d)-Sm(5d)电子间的直接交换作用，导致了Sm-Co间的磁性交换耦合，这是化合物中形成Sm-Co铁磁性长程序的一个重要原因.在SmCo5_{5化合物中存在6个能级呈现负交换耦合，导致了SmCo55化 关键词： 电子结构 自旋极化 原子磁矩 交换耦合}

Studies on the electronic structures, exchange coupling and magnetic moments of spin and orbital in the compound SmCo55

The electronic density of states, spin-splittings and atomic magnetic moment of RE-TM compound SmCo5₅ have been studied by spin-polarized MS-Xα method. The results show that a few of electrons are transferred to Sm(5d0⁰) o rbital because of orbital hybridization between Sm and Co atoms in the compound. The exchange interactions between 3d and 5d electrons lead to the magnetic coupling betwee n Sm and Co, and therefore, result in the long-range ferromagnetic order inside the compound SmCo5₅ There are some negative exchange couplings occ urring at six levels, which make the Curie temperature of SmCo5₅ decrease disti nctly, com pared with pure Co. The spin moment and orbital moment of 2c and 3g site s have been also studied in this paper. We found that the spin moment, orbital m oment and its quenched part of Co(2c) are greater than that of Co(3g).Th erefore, the strength of L-S coupling of the former is a little greater tha n that of the latter, which implies the contribution to magneto-anisotropy of 2c site is greater than that of 3g site. But the unquenched orbital mome nt in 2c site is slightly smaller than that in 3g site. So, the differen ce of contribution to the anisotropy between the two Co-sites is not very disti nct. Considering the localization of 4f electrons and the few 5d electrons, the magnetic moment of Sm atom will be 129μB_B in SmCo5₅, wh ich is in agreem ent with the experiments of Sm3+³⁺ ion-moment (132—163μB_B) and the Sm atom-moment (174μB_B) in metal.