Effects of Y atom substitution on the structural, magnetic, electronic, elastic, mechanical, thermodynamic and thermoelectric properties of Co2YAl (Y = Cr, Mn) Full Heusler alloys from first principles investigations

Many Heusler alloys have been discovered experimentally and theoretically, particularly, Co-based ones, owing to the growing attributes driven interests and suitabilities in spintronics. In this study, first principles calculations via generalized gradient approximations (GGA), with treatment of the electron-ion interactions using Kresse-Joubert Projected Augmented wave (KJPAW) pseudo-potentials were performed to comparatively and extensively investigate the effects of substituting Cr with Mn in Co2CrAl full Heusler alloy on their structural, magnetic, electronic, elastic, mechanical, thermodynamic and thermoelectric properties. Linear fitting of the stress-strain relationships of these cubic alloys at their respective optimized lattice parameters yielded three elastic constants, from which other mechanical parameters were obtained. Thermodynamic properties were determined from the Quasi-harmonic approximations in the framework of Debye model and non-spin polarized calculations as implemented in BoltzTraP code, gave thermoelectric properties in the temperature range of 0 and 800 K. Results obtained at ground states agreed reasonably with available data from experimental and theoretical investigations, and these revealed that the substitutive effects on these investigated properties were prominent in magnetic moments and half-metallicities, indicators of enhancements for spintronic applications and in thermoelectric figure of merits. These two alloys were ductile with metallic bonding systems and structurally, mechanically and thermodynamically stable in these investigative temperature ranges. (C) 2019 Elsevier B.V. All rights reserved.