The Co^2+-Ir^5+ Orbital Hybridization in LaCaCoIrO_6 Double Perovskite

Here, we report on the structural, electronic, and magnetic properties of a polycrystalline sample of the LaCaCoIrO_6 double-perovskite investigated by means of synchrotron x-ray powder diffraction, x-ray absorption spectroscopy, and x-ray magnetic circular dichroism at the Co and Ir L_2,3 edges, magnetometry, and electrical transport. Our results indicate a configuration of nearly Co^2+/Ir^5+ configuration for the transition-metal ions, with spin canting within the Co antiferromagnetic superstructure responsible for the ferromagnetic-like behavior observed below 100 K. The highly insulating character of LaCaCoIrO_6 and its positive magnetoresistance further suggest that this antiferromagnetic superexchange interaction occurs through an indirect hybridization between the Co e_g orbitals