摘要:
基于密度泛函理论的第一性原理计算,研究了横截面为五边形和六边形的核壳结构硅纳米线的过渡金属Co原子替代掺杂。通过比较形成能发现,核心位置掺杂、壳层单链掺杂以及外壳层全替代掺杂的硅纳米线都具有稳定性,其中核心位置掺杂结构的稳定性最高。掺杂体系均呈现金属性,随着掺杂浓度的增加,电导通道数增加。 Co原子掺杂的硅纳米线呈现铁磁性,具有磁矩。 Bader电荷分析表明,电荷从Si原子转移至过渡金属Co原子。与自由态时过渡金属Co原子的磁矩相比,体系中Co原子的磁矩有所降低,这主要是由Co原子4s轨道向3d/4p轨道的电荷转移以及4s,3d,4p的上自旋电子转移至下自旋导致的。
Abstract:
According to density functional first-principles calculations, we study the substitutional doping of Co atoms in core-shell silicon nanowires. By comparing the formation energies, we find that all the doping configurations obtained from shell-chain doping, core doping, and whole shell doping are stable, and core-shell doping silicon nanowire has the highest structural stability. All the doped configurations show metallic property, and the conductance channels increase with the increasing of doping concentration. Co-doped silicon nanowires show ferromagnetic, possessing magnetic moment. Bader charge analysis shows that charge is transferred from Si atoms to Co atoms in doped silicon nanowires. In transition metal Co atom, charge is transferred from 4s orbital to 3d and 4p orbital. The reducing of unpaired electron in 3d orbital and part of charge transferring from up-spin to down-spin in 4s, 3d and 4p orbital, makes magnetic moments in Co atom reduced.
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