【摘要】 使用基于密度泛函理论的第一性原理方法,优化了闪锌矿结构的Cr_xZn_1-xSe（x=0.000,0.125,0.250和0.375）的2×2×2超胞的几何结构,计算了其自旋极化的态密度和能带结构、离子磁矩、电荷分布等磁电性能,详细分析了Cr含量对Cr_xZn_1-xSe磁电性能的影响.结果表明,Cr掺杂后ZB型ZnSe具有明显的半金属特性;当x=0.125,0.250和0.375时,Cr_xZn_1-xSe均有较宽的半金属带隙,从而可能具有较高的居里温度;当x=0.125时,Cr_xZn_1-xSe的半金属性最稳定;x=0.125,0.250和0.375时,Cr_xZn_1-xSe的超胞磁矩分别为整数磁矩4.0,8.0和12.0μ_B,而具有整数磁矩是半金属铁磁体非常重要的特征之一.Cr_xZn_1-xSe的半金属性和磁性主要来源于Cr离子的自旋极化,Cr离子的电子结构为Cr e_g²↑e_g¹↓t_2g³↑.更多还原

【Abstract】 The geometrical structures of 2×2×2 Cr_xZn_1-xSe （x= 0.000,0.125,0.250 and 0.375） supercells were optimized based on the density functional theory.Then their magnetic and electric properties, including the spin-polarized state densities and band structures,the ionic magnetic moments and the charge distribution were calculated and analyzed systematically.The infulence of Cr-content on the electric and magnetic properties of the half-metallic ferrimagnets were analyzed.Results show that the Cr-doped ZB Cr_xZn_1-xSe have evident half-metallicity.Cr_xZn_1-xSe （x = 0.125,0.250 and 0.375） have wide half-metallic band gaps,then potentially have high Curie temperatures.The half-metallicity of Cr_xZn_1-x Se is most stable if x = 0.250.The supercell magnetic moments of Cr_xZn_1-xSe （x= 0.125, 0.250 and 0.375） are 4.0,8.0 and 12.0 μ_B,respectively.These supercell magnetic moments are integral. Having inetegral mangetic moments is one of important half-metallic characters of materials.The half-mataillicity and supercell magnetic moments mainly come from spin-polarization of Cr-ions.The electronic structures of Cr-ions are Cr e_g^↑e_g¹↓t_2g³↑.更多还原