过渡金属元素Sc、Cr和Mn对Mg2Ge掺杂的第一性原理研究

基于密度泛函理论(DFT)的第一性原理计算，研究了过渡金属元素Sc、Cr和Mn掺杂对Mg₂Ge晶体光、电、磁性质的影响。结果表明，Sc掺杂能使Mg₂Ge的费米能级进入导带，呈n型简并半导体；Cr和Mn掺杂能使Mg₂Ge能带结构和态密度在费米能级附近产生自旋劈裂而形成净磁矩，表现为半金属磁体和稀磁半导体，体系净磁矩均来自杂质原子3d轨道电子及其诱导极化的Ge4p态和Mg2p态自旋电子。与本征Mg₂Ge相比，掺杂体系静态介电常数增大，扩展了吸收光谱，提升了近红外光波段吸收能力。

First Principles Study on Mg2Ge Doping with Transition Metal Elements Sc, Cr, and Mn

In this study, the electronic structures and magnetic and optical properties of Mg₂Ge doping with transition metal elements X (X=Sc, Cr, and Mn) were investigated by density functional theory (DFT). The lattice constants, band structures, density of states, and optical parameters were calculated for all compounds. The results show that the Fermi level of Mg₂Ge can enter into the conduction band after doping with Sc, and Mg₂Ge turns into an n-type degenerate semiconductor. It can lead to spin splitting of the band structure and density of states of Mg₂Ge near Fermi level after doping with Cr and Mn, resulting in a net magnetic moment, which is shown as a semi-metallic magnet and dilute magnetic semiconductor. The net magnetic moment of the system is derived from the 3d orbital electrons of impurity atoms and their induced polarization of Ge4p state and Mg2p state spintronics. Compared with the intrinsic Mg₂Ge, the doping systems have an improvement in the static permittivity, which indicates that the photocatalytic activity of Mg₂Ge is enhanced. In terms of the absorption coefficient, the compounds with impurity atoms extend the absorption range, and the best enhancement appears near-infrared band.