Ferromagnetic Mott-Insulating State in Double Perovskites Gd₂ MgIrO₆

We have studied the electronic and magnetic properties of double perovskites Gd₂MgIrO₆ by first-principles density functional theory (DFT). Based on the DFT calculations, Gd₂MgIrO₆ is found to have a ferromagnetic (FM) ground state. The material undergo half-metallic ferromagnets to Mott-Hubbard insulator transition which happens due to strong correlation in Gd–4f and Ir–5d states. Our results shows that the 5d electrons of Ir hybridize strongly with O–2p states near the Fermi level giving rise to the insulating state of Gd₂MgIrO₆. Our study suggests that the enhanced magnetic moment is a result of itinerant exchange rather than the exchange interaction involving individual ions of Gd and Ir atoms. The total magnetic moment calculated in the present studies is 15 μ_B per formula unit for Gd₂MgIrO₆.