Spectroscopic profiles of a magnetic dimer on a metal surface

To better understand the Scanning Tunneling Spectroscopy (STS) spectra for a magnetic dimer on a metal surface, we calculate the differential conductance ( d I / d V ) based on the model Hamiltonian corresponding to an available experimental set-up. Our results show that the ferromagnetic RKKY interaction sharpens the Yosida–Kondo resonance and, on the other hand, the antiferromagnetic RKKY interaction gradually broadens the Yosida–Kondo resonance, as observed in the experiments. These results indicate a smooth transition from the Kondo effect dominating regime to the RKKY interaction dominating regime for the surface system we have considered.