Heusler合金Co2YZ（Z=Si，Al，Ge，Ga）半金属性的第一原理研究

应用基于密度泛函理论（DFT）的投影扩充波函数（PAW）方法，分别在广义梯度近似GGA和GGA＋U（在位库仑能）近似下，研究了Heusler合金化合物Co2YZ（Z=Si，A1，Ge，Ga）的晶体结构、电子结构和磁性等物理性质．发现Heusler合金Co2YSi在平衡晶格常数时显示了亚铁磁半金属性质，并且在一定程度的晶格常数变化范围内保持其半金属性质．另外Co原子的磁矩对局域环境具有很强的依赖关系，即Z位元素的变换很大程度影响Co原子的磁矩．

First-principles Studies of the Half-metallicity of the Full-Heusler Alloys: Co2YZ(Z=Si,Al,Ge,Ga)

Using the projected augmented wave(PAW) method within the generalized gradient approximation(GGA) and GGA U(on-site Coulomb interaction) respectively by density-functional theory(DFT),we study the equilibrium structural,electronic and magnetic properties of the full-Heusler alloysCo2YZ(Z=Si,Al,Ge,Ga).The full-Heusler alloyCo2YSi shows the half-metallic ferromagnet(HMF) behavior at the equilibrium latticeconstants.We show that small compression and expansion of the calculated theoretical equilibrium lattice constants restores the half-metallic ferrimagnetism for the full-Heusler alloy Co2YSi.Moreover,the magnetic moment of the Co atom depends on the local condition extraordinarily that the magnetic moment carried by Co atoms is restricted by the Z atoms.