Contribution of Degenerate Molecular Orbitals to Molecular Orbital Angular Momentum in Molecular Magnet Fe(Pc)(CN)₂

Abstract

We measured the static magnetic susceptibility and the electron spin resonance of the Fe(Pc)(CN) 2 complexes, and investigated the molecular magnetism of the unit Fe(Pc)(CN) 2 . The magnetic susceptibility shows a highly anisotropic Curie behavior. Based on the electron spin resonance, we found a highly anisotropic g -value ( g 1 = 3.62, g 2 = 1.11, and g 3 = 0.52) in the molecular unit Fe(Pc)(CN) 2 . This anisotropy is caused by the molecular orbital angular momentum in the degenerate next highest occupied molecular orbitals of the molecular unit Fe(Pc)(CN) 2 . Since the molecular unit Fe(Pc)(CN) 2 has a unique structure with fourfold symmetry, the molecular orbital angular momentum has a finite value of l z ∼+1 and -1. The anisotropic molecular magnetism of the unit Fe(Pc)(CN) 2 contributes the highly anisotropic Curie behavior. The molecular unit Fe(Pc)(CN) 2 is a good candidate for a molecular magnet having high magnetic anisotropy.