摘要:
通过基于密度泛函理论的广义梯度近似GGA＋U方法对铁磁相SrCoO3的电子结构和磁学性质进行了系统研究.结果表明：随着U值的增大,对于Co离子,主自旋方向的t2g和eg态向低能级移动,而次自旋方向的t2g和eg态向高能级移动;O 2p电子态的分布基本不随U变化.能带结构表明,U大约在7—8 eV之间时,SrCoO3由金属性转变为半金属性.U值小于7 eV时,Co离子的磁矩随着U值的增大几乎成线性增大,而当U大于7 eV后基本保持不变.结合实验结果,本文认为U取8 eV时得到的计算结果更为合理,Co离子的磁矩为3.19μB,且SrCoO3表现出半金属特性.
Abstract:
Using density functional calculations within the generalized gradient approximation and Hubbard U framework,the electronic and the magnetic properties of SrCoO3 are investigated.The result shows that the spin-up t2g and e_g states of Co shift toward the lower energy with the increase of the U value,whereas the spin-down t_（2g0 and eg states of Co shift toward the higher energy.The O 2p state almost does not shift with the increase of U value.The electronic structure of SrCoO3 changes from metal state into half-metal state around U of 7-8 eV.The magnetic moment of Co ions increases linearly with U increasing for U7.0 eV,and almost does not change for U8.0 eV.Compared with the experimental results,U = 8.0 eV is thought to be suited for the study of SrCoO3.The result shows that with U = 8.0 eV,the magnetic moment on Co site is 3.19μb and SrCoO3 has the half-metallic nature.
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