Regular Article

L2₁ and XA ordering effect on phase stability, electronic structure, magnetic and thermodynamic properties in Scandium-Based Full-Heusler Alloys Sc₂CoZ (Z = Al, Ga, In)

¹ Ecole Normale Supérieure d’Oran, BP 1063 Saim Mohamed, Oran 31003, Algeria
² Department of materials sciences, Sciences institute, Belhadj Bouchaib University Center, BP 284, Ain Temouchent 46000, Algeria
³ Laboratory of Physical Chemistry of Advanced Materials, University of Djillali Liabes, BP 89, Sidi-Bel-Abbes 22000, Algeria

^a e-mail: salem.hebri@gmail.com

Received: 12 June 2020
Received in final form: 27 August 2020
Accepted: 7 October 2020
Published online: 2 December 2020

Abstract

Site preference of transition metal elements habitually determined by the number of their valence electrons has been extensively used in the design of the full-Heusler alloys X2YZ. In this work, the full-Heusler materials Sc₂CoZ (Z = Al, Ga, In) were investigated and the comparison between the L2₁ and XA types structures of those alloys were studied based on first-principles calculations. The ferromagnetic L2₁ structure is found to be energetically more favorable than the XA structure. The phonon dispersion curve predicts that all alloys are dynamically stable in L2₁ structure. The influence of atomic ordering with respect to the Wyckoff sites on the phase stability, electronic structure and magnetism were also analyzed. Nearly half-metallic behavior is observed for the L2₁-type. However, XA-type is nonmagnetic semiconductor. For L2₁-type, all alloys have a weak magnetic moment at equilibrium lattice parameter, mainly attributed to the Co atom. Thermodynamic properties of both types of structure are studied using quasi-harmonic Debye model.