MnGa合金体的电子结构与磁性质的研究

Electronic Structure and Magnetic Properties of MnGa Alloy

基于密度泛函理论方法系统研究了四方结构MnGa合金体的结构、形成、电子结构和磁性质。结果表明,四方MnGa合金晶胞的生成焓为-4.85 eV,高于一些不含d电子的体系。其呈现导体的能带结构,其中d电子主要形成深能级价带,定域性最强。四方MnGa合金存在着明显的自旋极化,靠近费米能级两侧的s电子和靠近费米能级下方的p电子具有较弱的自旋极化。形成浅能级价带和导带的d电子产生高强度的自旋极化,对磁性质贡献较大。Mn的s电子和Mn的p电子自旋极化作用较弱,Mn的d电子形成浅能级价带和导带,自旋极化作用最强。形成深能级价带的Ga的d电子自旋极化作用较弱,不同位置的Ga原子的自旋极化不同。四方MnGa合金体具有净有效磁矩,呈弱的亚铁磁性。

Geometry,formation,electronic structure as well as magnetic properties of the tetragonal MnGa alloy were systematically studied by density functional theory method.The results show that the tetragonal MnGa has formation enthalpy of-4.85 eV,which is slightly higher than other compounds without d state electrons.It has conductor like band structure with the deep valance bands formed by d state electrons,they show strong localization effect.The tetragonal MnGa alloy shows obvious spin polarization.The s state electrons near Fermi energy and the p state electrons under Fermi energy have weak spin polarization,the d state electrons which form conductor band and bands below Fermi energy have strong spin polarization,they contribute to the total electronic as well as magnetic properties.The s and p state electrons of Mn have weak spin polarization,its d electrons which form conductor band and bands below Fermi energy have strongest spin polarization.The d electrons of Ga which form bands below Fermi energy have weak spin polarization.The two kinds of Ga have different spin polarization states.The tetragonal MnGa alloy has net magnetic moment,it shows weak ferrimagnetism.