Heusler合金Pd2CrAl四方变形、磁性及弹性常数的第一性原理计算

摘要

采用基于密度泛函理论的投影缀加波方法研究了Heusler合金Pd2CrAl的四方变形、磁性和弹性常数.四方变形中,Pd2CrAl在c/a≈1.20处出现总能的局域最小值,对应一个稳定的马氏体.Pd2CrAl的L21结构和四方结构的单胞总磁矩分别为3.825μB和3.512μB.在这两种结构中Cr原子均是Pd2CrAl总磁矩的主要贡献者,Pd和Cr原子间存在很强的杂化作用,Cr的3d电子的t2g和eg两个亚能带是Pd2CrAl磁性的主要来源.弹性常数的计算结果显示,Pd2CrAl的L21结构和四方结构的弹性常数均满足相应结构的稳定性判据.%Tetragonal distortion,magnetism and elastic constants of Pd2CrAl Heusler alloy are calculated by first principles based on the density function theory with projector augmented wave pseudopotential.Analysis of tetragonal distortion shows that there is a local minimum total energy at c/a≈1.20,which corresponds to a stable martensitic phase.The magnetic moments of formula unit cells for L21 and tetragonal structure are 3.825μB and 3.512μB,respectively.There is very strong hybridization between Pd and Cr,and magnetism originates mainly from the 3d-t2g and 3d-eg subbands of Cr atom in the two structures.Elastic constants of both L21 and tetragonal structure of Pd2CrAl satisfy their stability conditions,respectively.