Computational study of phase stability, electronic, magnetic and thermoelectric properties of a new quaternary Heusler alloy CrCoIrGa

Abstract

Exploring new materials with interesting physical properties plays a vital role in the development of modern technologies. Herein, using density functional theory based first-principles calculations, we present a study on the structural, electronic, magnetic and thermoelectric properties of a new quaternary Heusler alloy CrCoIrGa. The structure stability determined in terms of cohesive energy, formation energy and phonons dispersion curves confirms that alloy is stable and can be considered in experiments. The structural optimization in non-magnetic, ferromagnetic and antiferromagnetic state proves that alloy is ferromagnetic in the ground state with optimized lattice constant of 5.93 Å. The electronic band structure and density of states show that alloy is nearly half-metal (NHF) with 96% spin-polarization at the Fermi level. The effect of pressure on the electronic and magnetic properties investigated in the range 0–25 GPa, reveals that complete half-metallic character at the Fermi level can be obtained for pressure ≥10 GPa with a half-metallic gap of about 1 eV in the minority spin channel and a magnetic moment (Mt) of 3.0 μB/f.u., in agreement with Slater-Pauling rule (Mt = Zt-24). In addition, the electronic structures determined using DFT+U approach exhibit nearly half-metallic property such that amount of spin-polarization increases with increasing Hubbard parameter U. Finally, thermoelectric properties are examined by computing Seebeck coefficient (S), electrical conductivity (σ/τ), electronic thermal conductivity (κ) and power factor (PF) up to 800 K temperature. The positive value of S conveys that heat transport is carried by positive charge carriers. The room temperature values of S, σ/τ, κe/τ and PF are found to be about 5.9 μV/K, 3.06 × 1020 Ω−1m−1s−1, 2.27 × 1015 WK−1m−1s−1 and 1 WK−2m−1s−1, respectively. Collectively, these findings suggest that CrCoIrGa could play a useful role for the development of spintronics and energy production applications.