Evaluation of the Giant Ferromagnetic π–d Interaction in Iron-Phthalocyanine Molecule

摘要

The interaction between itinerant π and localized d electrons in metal-phthalocyanines, namely, J _(πd) interaction, is considered as responsible for the giant negative magnetoresistance observed in several phthalocyanine-based conductors, among many other important physical properties. Despite the fundamental and technological importance of this on-site intramolecular interaction, its giant ferromagnetic nature has been only recently demonstrated by the experiments conducted by Murakawa et al. in the neutral radical [Fe(Pc)(CN)_(2)]·2CHCl_(3) ( Phys. Rev. B 2015 , 92 , 054429). In this article, we present the theoretical evaluation of this interaction combining wave function-based electronic calculations on isolated Fe(Pc)(CN)_(2) molecules and density functional theory-based periodic calculations on the crystal. Our calculations confirm the ferromagnetic nature of the π–d interaction, with a coupling constant as large as J _(πd)/ k _(B) = 570 K, in excellent agreement with the experiments, and the presence of intermolecular antiferromagnetic interactions driven by the π–π overlap of neighboring phthalocyaninato molecules. The analysis of the wave function of the ground state of the Fe(Pc)(CN)_(2) molecule provides the clues of the origin of this giant ferromagnetic π–d interaction.