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用自旋极化的MS-Xα方法研究了化合物SmCo7-xTix的电子态密度、自旋能级劈裂及原子磁矩.研究表明,由于化合物中Sm-Co间的轨道杂化效应,使Sm(5d0)空轨道上占据了部分5d电子.5d-3d电子间的直接交换作用,构成Sm-Co间的主要耦合方式,这是在化合物中形成长程磁有序的一个重要因素.SmCo7-xTix的居里温度比金属Co明显降低,主要是因为2e位原子与其他原子之间存在着负交换耦合作用,从而使Co-Co之间交换劈裂平均值减少的缘故.研究结果也表明,掺杂原子Ti使2e位的负耦合作用减弱,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Fermi面处4f电子的扩展特征,以及化合物中轨道杂化效应所产生的部分5d电子,可以得到化合物总磁矩为9.47μB,与实验值基本符合.
The spin density MS-Xα method was used to study the electronic density of states, spin level splitting and atomic magnetic moments of the SmCo7-xTix compound. The results show that due to the orbital hybridization effect of Sm-Co in the compound, Sm (5d0) occupies a part of the 5d electrons on the empty orbit, and the direct exchange between 5d-3d electrons constitutes the main coupling mode of Sm-Co, which is an important factor for the formation of long-range magnetic ordering in the compounds.SmCo7-xTix The Curie temperature is lower than that of metal Co, which is mainly attributed to the negative exchange coupling between 2e atoms and other atoms, which leads to the decrease of average exchange splitting between Co-Co.The results also show that doped The heteroatom Ti weakens the negative coupling of 2e, and the electron bonding between Fermi surface increases and the system free energy of the compound decreases, which helps to form a stable ferromagnetic structure.According to the extended feature of 4f electrons at Fermi surface, As well as the 5d electrons generated by the orbital hybridization in the compound, the total magnetic moment of the compound can be 9.47μB, which is in good agreement with the experimental value.