Interplay of covalency, spin-orbit coupling, and geometric frustration in the d3.5 system Ba3LiIr2O9

*Jayita Chakraborty
Indian Institute of Science Education and Research Bhopal, Bhauri, Bhopal, India

The interplay of strong spin-orbit coupling, electron electron correlation, and crystal-field splitting in 5d transition metal oxides have recently attracted much attention both theoretically and experimentally. Here we investigate the electronic and magnetic properties of d3.5 iridate Ba3LiIr2O9 using first-principles electronic structure calculations. The results of the calculations reveal that the system lies in an intermediate spin-orbit coupling (SOC) regime. There is strong covalency of Ir-5d and O-2p orbitals. SOC, together with covalency, conspires to reduce the magnetic moment at the Ir site. By calculating the hopping interactions and exchange interactions, it is found that there is strong antiferromagnetic intradimer coupling within an Ir2O9 unit and other antiferromagnetic interdimer interactions make the system frustrated. The anisotropic magnetic interactions are also calculated. The calculations reveal that the magnitude of the Dzyaloshinskii-Moriya (DM) interactions parameter is small for this system. The effects of small electron and hole doping on DM interactions are also investigated here. The magnetocrystalline anisotropy energy is significant for this system, and the easy axis lies on the ab plane.