Engineering Spin Interaction Channels of FePc on Au(111).

We demonstrate the reversible control of interactions between a local molecular spin, hosted within an iron phthalocyanine (FePc) molecule, and the conduction electrons of a supporting Au(111) surface. Using the tip of a scanning tunneling microscope, we deliberately and reversibly manipulate the adsorption configuration of the molecule relative to the underlying substrate lattice. Different rotation configurations lead to noticeable changes in the differential conductance measured on the FePc molecules. In one configuration, a Kondo resonance is observed, while in others, spin excitations are revealed. To further explore the impact of the local environment, we designed a series of molecular assemblies in which neighboring molecules surrounding the target molecule are incrementally increased. In this structured approach, we observed a step-by-step transition of the spin excitation state to a Kondo resonance, ultimately resulting in a pure Kondo feature.