Electronic structure, cohesive, and magnetic properties of the actinide-iridium Laves phases

The electronic structure of the isostructural A${\mathrm{Ir}}_2$ systems (A=Th, Pa, U, Np, Pu, and Am) has been obtained by means of the scalar relativistic and fully relativistic linear muffin-tin orbital techniques. Ground-state properties such as lattice constants and onset of magnetic order have been calculated and compared with measured data. The hybridization between the actinide 5f and the ligand 5d states and the direct 5f wave-function overlap are found to be of comparable importance for the bandwidth of the itinerant 5f states. The anomalous paramagnetism of ${\mathrm{PuIr}}_2$ can be explained only by a fully relativistic treatment.