Heusler合金Mn_2NiAl的电子结构、磁性质及四方变形的第一性原理  

First-Principles of Electronic Structure and Magnetic Properties and Tetragonal Distortion of Heusler Alloy Mn_2NiAl

作　　者：罗礼进[1] 仲崇贵[1] 方靖淮[1] 杨建华[1] 周朋霞[1] 江学范[2] 

机构地区：[1]南通大学理学院,江苏南通226007 [2]常熟理工学院江苏省新型功能材料重点建设实验室,江苏常熟215500

出　　处：《吉林大学学报（理学版）》2012年第5期1015-1019,共5页Journal of Jilin University:Science Edition

基　　金：国家自然科学基金(批准号:10974104;30970754;11174043)

摘　　要：利用基于密度泛函理论的第一性原理,计算Mn2NiAl的晶体结构、四方变形、磁性、电子结构和压力响应.计算结果表明:Mn2NiAl在立方奥氏体相的平衡结构为铁磁态MnMnNiAl型结构,其中Mn原子占据A和B不等价晶位;在由立方结构向四方结构的变形中,在c/a≈1.24处存在一个稳定的马氏体相;在奥氏体相和马氏体相下,Mn原子对Mn2NiAl总磁矩的贡献最大,Mn(A)和Mn(B)原子磁矩的值不等并呈反平行耦合,且Mn(A)-d和Mn(B)-d的投影态密度在费米面附近交叠均较少,表明Mn(A)和Mn(B)原子间的d-d直接交换作用均较弱,而Mn原子内的交换作用较强,因此Mn2NiAl呈亚铁磁结构.Crystal structure, tetragonal distortion, magnetism, electronic structure and pressure response of MnzNiA1 were calculated by means of first-principles method based on the density functional theory. The calculation results show the equilibrium structure of Mn2NiA1 in the cubic austenitic phase is the MnMnNiA1 structure with Mn atoms occupying A and B non-equivalent positions. In the process of transform from a cubic to a tetragonal structure, Mn2NiA1 alloys exhibit a stable martensitic phase in c/a ~ 1.24. In both the austenite and martensite phases, the contribution of Mn atoms to the total moments for Mn2NiA1 is the largest, the magnetic moments of Mn （A） and Mn （B） atoms are inequality and antiparallel couple~ The direct d-d exchange interactions between Mn （A） and Mn（B） atoms are weak because of the small overlap of d-projected DOS of Mn（A） and Mn（B） atoms nearby the Fermi level, but the intra-atomic interactions in Mn atoms are strong, this is the reason why the Mn2NiA1 alloys show ferrimagnetism.

关 键 词：第一性原理 电子结构 亚铁磁 马氏体相 

分 类 号：O482.54[一般工业技术—材料科学与工程]