on Ag(111)

The single molecule magnet bis(phthalocyaninato)terbium(III) (TbPc₂) has attracted steady research attention as an exemplar system for realizing molecule based spin electronics. Lattices of these molecules interact through the π-electrons in their Pc ligands, which manifests itself experimentally as a Kondo resonance in spectroscopy measurements. Understanding these interactions is crucial for their subsequent use in quantum computing schema. We studied TbPc₂ molecules evaporated in ultrahigh vacuum onto a single crystal Ag(111) surface, measured at 5K using combined scanning tunneling and non-contact atomic force microscopies (STM/ nc-AFM). Submolecular resolution achieved with a CO- functionalized tip offers unprecedented structural information, specifically regarding the two sub-lattices forming tight-packed TbPc₂ islands. Kondo resonances are observed on molecules absorbed as a second layer on the larger TbPc₂ islands: the presence or absence of the Kondo signature is exactly correlated with the sub-lattice absorption site. Spectroscopies taken with a CO- terminated tip showed the Kondo resonance shifted to the center of the ligand. The latest efforts to understand the structural origin of this site-specific Kondo resonance will be reported.