Enhanced ferromagnetism in half-metallic CoIrZrAl quaternary Heusler alloy: A density functional study

The possibility of synthesis of the quaternary Heusler alloy CoIrZrAl is proposed on the basis of first-principles Density Functional calculations. The equilibrium lattice constant , assuming F-43 m lattice symmetry, is calculated and the Bulk modulus obtained is very close to that of C o 2 ZrAl (Essaoud and Jbara, 2021). CoIrZrAl Heusler alloy is predicted to be a half-metal having an energy gap of 0.7632 eV between t 1 u and e u state in the spin down channel. The ferromagnetic state is the magnetic ground state where the main source of total magnetic moment (= 1 μ B ) is the unpaired electron in the e u state derived from Co-3d and Ir-5d electrons. Upon 50% doping at the Co-site (3d) by an Ir atom having extended 5d state increases the mean field estimate of T C over Co 2 ZrAl. The charge density difference profile clearly establishes that the exchange mechanism is super-exchange between hybrid Co-3d electrons and Ir-5d electrons mediated by their hybridization with Zr-4d electrons. The partial replacement of the Co-3d electrons with less localized Ir-5d electrons leads to robust ferromagnetism and robust half-metallicity under hydrostatic pressure . • A new ferromagnetic half-metal CoIrZrAl has been predicted and its dynamic stability has been probed to prove its thermodynamic stability. • Mean-field Curie temperature of CoIrZrAl is found to be around 1000 K, much higher than that of its parent compound Co 2 ZrAl. • The spin-polarized charge density distributions show complex hybridization-mediated superexchange interaction among the Co-3d, Zr-4d and Ir-5d electrons. • Enhanced ferromagnetism as compared to that in Co 2 ZrAl is due to increased hybridization due to 50 % doping of 3d-Co atoms with delocalized 5d-Ir atom. • Half-metallicity is fairly robust with the application of hydrostatic pressure or volume expansion.