The Co$^{2+}$-Ir$^{5+}$ orbital hybridization in LaCaCoIrO$_6$ double perovskite

Abstract

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