【摘要】 用自旋极化的MS Xα方法研究了稀土 过渡族化合物SmCo5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 5d0 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化合物中存在 6个能级呈现负交换耦合 ,导致了SmCo5化合物的居里温度 (与金属钴相比 )明显下降 .还研究了化合物中 2c和 3g晶位Co的自旋磁矩和轨道磁矩 ,发现Co(2c)晶位的自旋磁矩、轨道磁矩及冻结部分均略大于Co(3g)晶位 ,所以 2c晶位的L S耦合强度应略大于 3g晶位 .因此 ,2c晶位对SmCo5磁晶各向异性的影响也应大于 3g晶位 .但Co(2c)未被冻结的轨道磁矩却略小于Co(3g) ,所以两种晶位对磁晶各向异性的贡献大小之差别不应太大 .考虑到 4f电子的局域性和化合物中轨道杂化效应所导致的Sm(5d0 )空轨道上占据了少量 5d电子 ,可以得到Sm原子磁矩为 1 2 9μB,与顺磁盐中Sm3+ 磁矩实验值 (1 32— 1 6 3μB)及金属中Sm原子磁矩实验值(1 74 μB)基本符合 .更多还原

【Abstract】 The electronic density of states, spin-splittings and atomic magnetic moment of RE-TM compound SmCo 5 have been studied by spin-polarized MS-Xα method. The results show that a few of electrons are transferred to Sm(5d 0) orbital 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 between Sm and Co, and therefore, result in the long-range ferromagnetic order inside the compound SmCo 5. There are some negative exchange couplings occurring at six levels, which make the Curie temperature of SmCo 5 decrease distinctly, compared with pure Co. The spin moment and orbital moment of 2c and 3g sites have been also studied in this paper. We found that the spin moment, orbital moment and its quenched part of Co(2c) are greater than that of Co(3g).Therefore, the strength of L-S coupling of the former is a little greater than 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 moment in 2c site is slightly smaller than that in 3g site. So, the difference of contribution to the anisotropy between the two Co-sites is not very distinct. Considering the localization of 4f electrons and the few 5d electrons, the magnetic moment of Sm atom will be 1.29μ B in SmCo 5, which is in agreement with the experiments of Sm 3+ ion-moment (1.32—1.63μ B) and the Sm atom-moment (1.74μ B) in metal.更多还原