新型Heusler合金RuMn2Sn的磁性形状记忆的第一性原理研究

摘要

The crystal structure, electronic structure, magnetism and tetragonal distortions of new Heu-sler alloy RuMn2 Sn are calculated by the first-principles method based on the density functional theory. The calculated results show that: 1) in austenite, Mn atoms are the main contribuors to the magnetism in RuMn2Sn, and RuMn2 Sn alloys show ferrimagnetism due to antiparallel but unbalanced magnetic moments of Mn(A) atom and Mn(B) atom; 2) in the process of transforrm from XA-type cubic to a tetrgo-nal, RuMn2 Sn alloys exhibit a stable martensitic phase at c/a≈1. 23 and show the anti-ferromagnetic properties; 3)in austenite and martensite, the weak direct d-d exchange interaction between Mn(A) atom and Mn(B) atom is the main reason to maintain ferrimagnetic and antiferromagnetic coupling effect between Mn(A) atom and Mn(B) atom. Based on the results of calculation above, we can predict the well magnetic shape memory effect in RuMn2Sn.%采用基于密度泛函理论的第一性原理方法,对新型Heusler合金RuMn2Sn的晶体结构、电子结构、磁性、四方变形等性质进行了系统的研究.研究结果表明:1)在奥氏体态下,磁性原子Mn对体系总磁矩的贡献最大,其中Mn(A)和Mn(B)原子磁矩的值不等并且呈反平行耦合,导致RuMn2Sn具有稳定的亚铁磁基态,该结果与实验一致；2)由XA型立方结构至四方结构的四方变形中,发现c/a约为1.23处存在一个能量更低的稳定的马氏体相,其呈现反铁磁的特性；3)在奥氏体态和马氏体态下,Mn(A)和Mn(B)原子之间弱的d-d直接交换作用是维持它们之间亚铁磁和反铁磁耦合的主要原因.根据上述计算结果,预测RuMn2Sn具有良好的磁性形状记忆效应.