LiMgPbSb型四元Heusler合金CrFeHfGa原子缺陷和无序效应

The Effect of Atomic Vacancy and Swap Defects in Quaternary LiMgPbSb-type Heusler Alloys CrFeHfGa

基于密度泛函理论的第一性原理计算,研究了LiMgPbSb型Heusler合金CrFeHfGa的原子缺陷及其无序效应。结果表明,原子之间交换无序以及Cr、Fe、Hf、Ga原子的25%缺陷对CrFeHfGa合金结构、磁性和自旋极化率都会造成不同程度的影响。对于原子缺陷,Ga原子缺陷具有最低形成能,但可以保留60%左右的自旋极化率;而Fe、Cr、Hf原子缺陷形成能相对较高,其中Hf缺陷可以保留86.58%的自旋极化率。对于原子交换无序,计算发现Ga-Hf和Cr-Fe无序形成能较低,在实验中出现的可能性较大。Cr-Fe交换无序结构可以保留92.43%的高自旋极化率,说明这种无序并不影响CrFeHfGa合金的自旋电子学应用。

The effect of atomic vacancy and swap defects in quaternary LiMgPbSb-type Heusler alloy CrFeHfGa were studied using the first-principles within density functional theory.The results show that the structure,magnetism and spin polarization of CrFeHfGa alloy were affected in various extents by atomic vacancy and swap defects.Ga atomic vacancy defect,retaining 60% spin polarization,had relatively lower formation energy;Fe,Cr atomic vacancy defects as well as Hf vacancy defect（86.58% spin polarization）had higher formation energy.Ga-Hf and Cr-Fe swaps were prefer to occur in experiment due to their very low formation energies,while the latter kept 92.43% high-spin polarization at the Fermi level,indicating that such swap defect may not affect spintronic application of CrFeHfGa alloy.