Ab-initio electronic, magnetic, and optical properties of Fe-phthalocyanine on NiO(001)

The adsorption of organic molecules on antiferromagnetic surfaces forms interfaces with potential applications in organic spintronics devices. Molecules modify the dispersion of spin excitations in the substrate through charge transfer and crystal deformations, and offer the possibility to couple them to light excitations. Here, we follow an ab initio approach to the study of the interface between the magnetic organo-metallic molecule Fephthalocyanine and the (001) surface of NiO. By applying Hubbard-corrected density-functional theory (DFT + U) calculations we determine the most stable adsorption configuration as that with the molecule lying flat with Fe above a surface O atom. We find a strong hybridization between Fe orbitals and surface ones, with the Fe spin coupled antiferromagnetically to subsurface Ni through the O atom. Moderate changes to the magnetic structure of the components and charge displacements are shown. Optical spectra show reduced absorption onsets and are investigated for the possibility of a coupling with the system spin properties.