Sb系half-Heusler合金磁性及电子结构的第一性原理研究

First-principles study of magnetism and electronic structure of Sb-containing half-Heusler alloys

采用基于密度泛函理论的第一性原理方法,计算了Sb系half-Heusler合金XYSb(X=Ni,Pd,Pt;Y=Mn,Cr)的晶体结构、磁性及电子结构.计算结果表明,在平衡晶格常数下,合金NiMnSb为半金属,其他为金属.合金的总磁矩主要由Y元素自旋磁距贡献,随着元素X原子序数减小,费米能级移向自旋向下能带导带底;压缩使费米能级上移,远离Sb原子p能带,PtMnSb,PdMnSb与NiCrSb在压应力下可实现金属—磁性半金属转变.

Using the first-principles density functional theory,we calculate the crystal structures,magnetisms and electronic structures of Sb-containing half-Heusler alloys XYSb（X = Ni,Pd,Pt;Y = Mn,Cr）.The calculation results show that alloy NiMnSb is half-metal and the others are metals at equilibrium lattice constant.The contribution of the spin magnetic moment of Y element to the total moment is largest for all alloys.It is found that the Fermi level of the minority spin band shifts closer to the bottom of spin-down conduction band with atomic number of X element reducing.The Fermi level moves up due to the compressive strain,away from p bands of Sb atom.Under the compresive stress,PtMnSb,PdMnSb and NiCrSb can induce metal half-metal transitions.