The electronic structures, magnetic and optical properties of Li_1±y(Mg_1−xCr_x) P (x, y = 0.125) are calculated by using the first principles method based on density functional theory. We find that the incorporation of Cr causes the strong hybridization between Li-2s, P-2p, and Cr-3d orbitals, resulting in a spin-polarized impurity band and forming stronger Cr-P polar covalent bonds. Li(Mg_0.875Cr_0.125)P becomes half-metallic ferromagnetism. The properties of the doped systems can be regulated by Li off-stoichiometry. When Li is deficient, the narrower impurity band and stronger p-d orbital hybridization enhance the half-metallicity. While the half-metallicity disappears, the band gap becomes wider, and the conductivity decreases for Li excess system, but its magnetic moments increase. Comparing optical properties show that the imaginary part of dielectric and complex refractive index function and optical absorption spectrum all have a new peak in the low energy region after Cr doping, and the new peaks are significantly enhanced when Li is deficient. The absorption range of low frequency electromagnetic wave is enlarged, and the energy loss functions show obvious red-shift effect for the doped systems. The results indicate that the properties of Li(Mg,Cr)P can be controlled by Cr doping and Li off-stoichiometry independently, which will benefit potential spintronics applications.

Li _1±的电子结构，磁和光学性质_ÿ（镁_1−X铬_X）P（，通过基于密度泛函理论的第一原理方法计算得出（= 0.125）。我们发现，Cr的掺入会引起Li-2s，P-2p和Cr-3d轨道之间的强杂化，从而导致自旋极化的杂质带并形成更强的Cr-P极性共价键。Li（Mg _0.875 Cr _0.125）P成为半金属铁磁性。掺杂体系的性质可以通过非化学计量的Li来调节。当Li不足时，杂质带越窄且越强p--d轨道杂交增强了半金属性。尽管半金属性消失了，但是带隙变宽了，而过剩的Li体系的电导率降低了，但是其磁矩却增加了。比较光学性能表明，掺杂Cr后，低能区的介电和复折射率函数的虚部和光吸收谱都有一个新的峰，当Li不足时，新的峰显着增强。低频电磁波的吸收范围扩大，能量损失函数对掺杂系统表现出明显的红移效应。结果表明，Li（Mg，Cr）P的性质可以通过Cr掺杂和Li的非化学计量独立控制，这将有利于自旋电子学的潜在应用。