新型稀磁半导体Mn掺杂LiZnAs的第一性原理研究

采用基于密度泛函理论的第一性原理平面波超软赝势方法, 对纯LiZnAs, Mn掺杂的LiZnAs, Li过量和不足下Mn掺杂的LiZnAs体系进行几何结构优化, 计算并对比分析了体系的电子结构、半金属性、光学性质及形成能.结果表明新型稀磁半导体Li (Zn_0.875Mn_0.125) As, Li_1.1 (Zn_0.875Mn_0.125) As和Li_0.9 (Zn_0.875Mn_0.125) As均表现为100%自旋注入, 材料均具有半金属性, Li过量和不足下体系的半金属性明显增强. Li过量可以提高体系的居里温度, 改善材料的导电性, 使体系的形成能降低. 说明LiZnAs半导体可以实现自旋和电荷注入机理的分离, 磁性和电性可以分别通过Mn的掺入和Li的含量进行调控. 进一步对比分析光学性质发现, 低能区的介电函数虚部和复折射率函数明显受到Li的化学计量数的影响. 关键词： Mn掺杂LiZnAs 电子结构 光学性质 第一性原理

First-priciples study on Mn-doped LiZnAs,a new diluted magnetic semiconductor

The electronic structures, half-metallic and optical properties, as well as formation energy of pure LiZnAs, Mn-doped LiZnAs and Mn-doped LiZnAs with excess and deficient of Li are geometrically optimized and calculated by using the first principle density functional theory based on the full potential linearized augumented plane wave method. Results show that in the systems of Li(Zn_0.875Mn_0.125)As, Li_1.1(Zn_0.875Mn_0.125) As and Li_0.9(Zn_0.875Mn_0.125)As a 100% spin injectors is revealed, and the materials exhibit half metallic. The half metallic materials with excess and deficient of Li are more stable than Mn-doped LiZnAs. Excess of Li could improve the Curie temperature and conductivity of the material, and cause the formation energy of the system decrease. So the separation of spin and charge injection mechanisms may be achieved in LiZnAs semiconductor, and the magnetic and electrical properties of diluted magnetic semiconductor may be regulated respectively by Mn doping and Li stoichiometry. In addition, the dielectric function and the complex refractive index function in the low-energy region are found to be influenced by the stoichiometry of Li.
Keywords： Mn-doped LiZnAs electronic structures optical properties first-principle