Tuning the spin-related transport properties of FePc on Au(111) through single-molecule chemistry.

Tuning the spin-dependent electron transport through molecules is of fundamental importance in single-molecule spintronics. Here, the transport properties of iron phthalocyanine on Au(111) was investigated by a combination of scanning tunneling microscopy and density functional theory calculations. Using high-resolution scanning tunneling spectroscopy performed at 0.5 K, a Kondo resonance was observed on FePc. After removing its eight outermost hydrogen atoms, the spectroscopic feature changed into a double-step structure, which reflected inelastic transitions of molecular spin states. The density functional theory calculations revealed that the coupling between Fe and Au(111) became much weaker after cutting the hydrogen atoms. This explained the change of the spin-related fingerprints in the differential spectra.