Eur. Phys. J. Plus (2021) 136: 1147
https://doi.org/10.1140/epjp/s13360-021-02091-7

Regular Article

Effect of Ga excess concentration on the structural, electronic, magnetic, elastic and thermoelectric properties of Fe_2−xNiGa_1+x Heusler alloys: results of FP-LAPW calculations

¹ Department of Physics, Faculty of Science, University Ferhat Abbas Setif 1, 19000, Setif, Algeria
² Laboratoire dEtude Des Surfaces Et Interfaces Des Matériaux Solides, University Ferhat Abbas Setif 1, 19000, Setif, Algeria
³ Department of Physics, Faculty of Science, University of Msila, 28000, Msila, Algeria
⁴ Laboratory of Physics and Chemistry of Materials, University of Msila, Msila, Algeria

^a sachami_dz@yahoo.fr

Received: 20 July 2021
Accepted: 18 October 2021
Published online: 15 November 2021

Abstract

The structural, electronic, magnetic, elastic and thermoelectric properties of Fe_2−xNiGa_1+x (x = 0, 0.25, 0.5, 0.75, 1) Heusler alloys are investigated through ab initio calculations based on density functional theory (DFT) within the full potential linearized augmented plane wave (FP-LAPW) method. After substituting Fe by Ga in the unit cell, we find that the composition dependence of both the lattice constants and bulk modulii are not monotonous. Moreover, while these alloys still keep their metallic character, the calculated electronic structure shows an increase in the p–d and a corresponding decrease in the d–d orbital hybridizations between the transition metal and the main group elements. The distribution of the spin magnetic moments shows that these materials are ferromagnetic with their respective magnetic moments and Curie temperatures decreasing linearly with the Ga excess concentration x. The Fe_2−xNiGa_1+x Heusler alloys (x = 0, 0.25, 0.5, 0.75, 1) we studied, are all found to be mechanically stable and, because of their high B/G ratio, ductile. The BoltzTraP code is used to assess the influence of Fe substitution by Ga on the transport properties. The Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit for the Fe_2−xNiGa_1+x alloy are all calculated.