Robust pure spin currents in a binuclear ferric phthalocyanine junction driven by the photogalvanic effect

The investigation of optical methods for generating pure spin current at the molecular level is of critical importance. We investigated the spin-related photocurrent produced by the photogalvanic effect in a binuclear ferric phthalocyanine (Fe2Pc2) junction with spatial inversion symmetry. When the magnetic moment directions of Fe atoms at the center of each phthalocyanine are in parallel configuration (PC) or antiparallel configuration (APC), the molecular junction exhibits different photoresponses. In contrast to the PC, which lacks both charge and spin current, the APC produces pure spin current. Additionally, the pure spin current exhibits robustness with respect to polarization type and polarization angle. This difference in characteristics between the PC and APC stems from the different symmetry of their spin densities, which can be altered by the direction of the magnetic moments of two Fe atoms at the center of the molecule.