On-surface structural and electronic properties of spontaneously formed Tb2Pc3 single molecule magnets

Abstract

The single molecule magnet (SMM) bis(phthalocyaninato)terbium(III) (TbPc₂) has received significant and increasing attention as an exemplar system for realizing molecule-based spin electronics. Attaining higher nuclearity via multi-decker TbPc systems has remained an outstanding challenge, as known examples of Tb₂Pc₃ systems are only those containing Pc rings with substituents (e.g. alkyl, alkoxyl). Here we report on the spontaneous formation of Tb₂Pc₃ species from TbPc₂ precursors via sublimation in ultrahigh vacuum (UHV) onto an Ag(111) surface. The presence of Tb₂Pc₃ molecules on the surface are inspected using scanning probe microscopy with submolecular resolution supported by density functional theory (DFT) calculations and additional chemical analysis. We observe the selective presence of a Kondo resonance (30 K) in the Tb₂Pc₃ species, that we attribute to differences in the orientation of the internal molecular ligands. Formation of triple-decker complexes offers new possibilities to study and control magnetic interactions not accessible with standard TbPc₂ molecules.