On the possibility of low-symmetry structures in Zr2CoSi

• Published in: Journal of magnetism and magnetic materials Vol. 587; p. 171319
• Main Author: Pugaczowa-Michalska, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2023
• Subjects: Elastic constances; Electronic structure; Heusler compound; Mechanical stability; van Hove singularity; van Hove singularity; Heusler compound; Elastic constances; Electronic structure; Mechanical stability
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2023.171319

•The L21 structure is energetically more favorable in Zr2CoSi than the Hg2CuTi one.•The DOS of Zr2CoSi in L21 structure have van Hove singularity.•The elastic constants of Zr2CoSi in L21 structure indicate a mechanical instability.•There are two tetragonal and one orthorhombic distorted phases of Zr2CoSi that are energetically favored.•The tetragonal phase of Zr2CoSi with c/a > 1.0 fulfills elastic stability conditions. First principles calculation shows that the energy difference between the cubic L21 and Hg2CuTi inverse structure for Zr2CoSi is 1.454 eV/f.u., indicating than the L21 structure is more stable. The density of states and band structure of Zr2CoSi in the L21 structure do not support the half–metallic state. Moreover, van Hove singularity involving partially occupied Co 3d eg states occurs in minority states at the Fermi level and the Zr2CoSi in L21 structure satisfies the preconditions to exhibit a cubic-to-tetragonal instability according to a band-Jahn-Teller mechanism. The computed total energy landscapes of the system shows that there are two tetragonal and one orthorhombic distorted phases of Zr2CoSi that are energetically favored over the undistorted cubic L21 structure. However, only one tetragonal phase of Zr2CoSi with c/a > 1.0 fulfills necessary and sufficient elastic stability conditions for both GGA and LDA exchange–correlation potentials.