Heusler合金M2CoA(M=Mn,Ti;A=Al,Si)的第一性原理

采用基于密度泛函理论(DFT)的第一性原理计算方法,研究了M₂CoA型Heusler合金Mn₂CoAl、Mn₂CoSi、Ti₂CoAl和Ti₂CoSi的电子结构和磁学性质。发现Heusler合金Mn₂CoAl是亚铁磁性自旋无带隙半导体,Mn₂CoSi与Ti₂CoAl是亚铁磁性自旋半金属,而Ti₂CoSi是铁磁性自旋半金属。它们的总自旋磁矩均为整数,符合Slater-Pauling规则。然后,在分析电子能带结构和态密度的基础上,探讨了自旋无带隙半导体与半金属性的根源。最后,声子谱和弹性常数计算结果表明所有M₂CoA型Heusler合金在晶格动力学和力学上均是稳定的。

First-principles investigation of Heusler alloys M2CoA(M=Mn,Ti;A =Al,Si)

The electronic structure and magnetic properties of the M₂ CoA type Heusler alloys Mn₂CoAl, Mn₂CoSi, Ti₂CoAl and Ti₂CoSi were systematically investigated using first-principles calculations based on the density functional theory. The results show that Mn₂CoAl is a ferrimagnetic spin gapless semiconductor; Mn₂CoSi and Ti₂CoAl are ferrimagnetic spin half-metals, while Ti₂CoSi is a ferromagnetic spin half-metal. The total spin magnetic moments of the M₂CoA type Heusler alloys are integers, obeying the Slater-Pauling rule. By analyzing the band structures and electronic density of states, the origin of spin gapless semiconductor as well as half-metal were revealed. The calculation results of phonon dispersion curves and elastic constants show that all the M₂CoA type Heusler alloys are stable in the lattice dynamics and mechanics.