Strain-driven half-metallicity in a ferri-magnetic Mott-insulator LuNiIrO: a first-principles perspective.

Half-metallic ferromagnetic/ferrimagnetic (FiM) materials are a matter of enormous interest due to their potential technological applications in solid-state electronic devices. In this way, strain plays an important role to tune or control the physical properties of the systems; therefore, the influence of both biaxial ([110]) and hydrostatic ([111]) strain on the electronic and magnetic properties of recently synthesized double perovskite oxide Lu2NiIrO6 is investigated using density-functional theory calculations. The unstrained system exhibits a FiM Mott-insulating (i.e., having an energy gap of 0.20 eV) ground state due to strong antiferromagnetic superexchange coupling between high-energy half-filled Ni2+-e2g↑ and low-energy partially filled Ir4+ t32g↑t22g↓ orbitals. Interestingly, a half-metallic FiM state is predicted under biaxial and hydrostatic compressive strains of -8% and -6%, respectively. The admixture of Ir 5d orbitals in the spin-majority channel is mainly responsible for the conductivity with small contributions from Ni 3d orbitals. In contrast, all the tensile strain systems show almost the same electronic behavior (Mott-insulating FiM states) as found in the case of the unstrained system. The magnetic moments of the Ni (Ir) ion slightly decrease and increase as a function of compressive and tensile strains due to shortening and lengthening of the Ni-O(Ir-O) bond lengths, respectively. Moreover, our calculations show that compressive strain enhances the structural distortions, which could help to increase the Curie temperature of the system.