First-principles investigation of mechanical and electronic properties of MFeAs (M = Cu, Li, and Na)

• Published in: Journal of applied physics 2016-12, Vol.120 (23)
• Main Authors: Chen, Z. J., Xu, G. B., Yan, J. G., Kuang, Z., Chen, T. H., Li, D. H.
• Format: Article
• Language: English
• Subjects: Applied physics; Banded structure; Bulk modulus; Copper; Density of states; Energy levels; First principles; Lattice parameters; Mathematical analysis; Mechanical properties; Modulus of elasticity; Phase transitions; Shear modulus; Sodium; Superconductivity
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4969042

Mechanical and electronic properties of Cu2Sb-type compounds MFeAs (M = Cu, Li, and Na) have been studied by the first-principles calculations. The main trends in structure parameters, mechanical parameters, electronic bands, and densities of states (DOS) for MFeAs are analyzed according to the variable cation M sites. Our results show that the lattice constants increase, while the bulk modulus, shear modulus, and Young's modulus decrease with the increasing radii of M sites in the sequence CuFeAs → LiFeAs → NaFeAs. Mulliken overlap population indicates that different M atoms in MFeAs (M = Cu, Li, and Na) would influence the bond nature of Fe-As, which may induce the superconductivity. The disappearance of the hole-pockets affects the superconductivity in CuFeAs. Although the value of the DOSs N(EF) at the Fermi level grows with decreasing radii of M sites, it is not the only factor influencing the superconductivity. Due to the repulsive interaction between Cu-3d and Fe-3d states in CuFeAs phase, it would change the position of Fe-3d orbits and Fermi energy level after introducing Cu in this structure. Therefore, after introducing Cu in the structure would induce the different position of Fe-3d states and Fermi energy level. Therefore, we believe that the component M has an important influence on the superconductivity.