新型稀磁半导体Mn掺杂LiZnP的电子结构和光学性质

采用基于密度泛函理论的第一性原理计算方法,对纯LiZnP、Mn掺杂LiZnP、Li过量和不足时Mn掺杂LiZnP体系进行了几何结构优化,计算并分析了体系的电子结构、半金属性、态密度及光学性质.结果表明:LiZnP新型稀磁半导体可以实现自旋和电荷注入机制的分离.Mn的掺入使体系产生自旋极化杂质带,自旋极化率达到100%,表现出半金属铁磁性,且体系性质受Li计量数的影响.当Li不足时杂质带宽度增大,半金属性增强,居里温度提高,形成能最低.进一步比较光学性质发现:Mn掺入后体系光学性质没有明显变化,但随Li的化学计量数的改变,介电函数虚部会在低能区中出现新的介电峰,同时复折射率函数对低频电磁波吸收明显加强,且能量损失在Li过量时最小.

Electronic Structures and Optical Properties of Mn-doped LiZnP New Diluted Magnetic Semiconductors

Using first-principles calculation method based on density functional theory, the geometric structures of pure LiZnP, Mn-doped LiZnP, and Mn-doped LiZnP with excess and insufficient of Li are optimized. Their electronic structures, half-metallic properties, formation energies and optical properties are calculated. It indicates that Mn doping produces spin polarized impurity bands, and the spin polarized rate is 100%. The system exhibits half-metallic ferromagnetic properties, affected by the content of Li. In Li insufficient compound, the width of impurity band, half metallic, net magnetic moments, and Curie temperature increase, meanwhile the formation energy decreases. All these show that the LiZnP new semiconductor is a realistic candidate with decoupled doping, in which charge and spin can inject separately. By comparing the optical properties, it finds that the dielectric function did not change significantly after Mn doped, but new dielectric peaks appear in the low energy region with Li stoichiometric changing, and energy loss decreases obviously for Li excess system.