Spin states and their relaxation in transition-metallorganic self-assembled molecules

The coexistence of spins localized on transition-metal ions and mobile charges on the $\pi $-conjugated ligands in transition-metallorganic self-assembled molecules (TMSAMs) makes these molecules attractive for molecular spintronic devices and quantum computing. We present our theoretical results on the spin states localized on the transition-metal ion in a TMSAM using both the first-principles approaches and the ligand-field theory. Then we construct a spin Hamiltonian to calculate spin lifetimes and identify the dominant spin relaxation mechanisms in the molecule. We also discuss the relation between the spin states on the transition-metal ion and the charge transport along the $\pi $-conjugated ligand in the molecule.