Surface states influence in the conductance spectra of Co adsorbed on Cu(111)

Abstract

We calculate the conductance spectra of a Co atom adsorbed on Cu(111), considering the Co 3d orbitals within a correlated multiple configurations model interacting through the substrate band with the Co 4s orbital, which is treated in a mean-field like approximation. By symmetry, only the d z 2 orbital couples with the s orbital through the Cu bands, and the interference between both conduction channels introduces a zero-bias anomaly in the conductance spectra. We find that, while the Kondo resonance is mainly determined by the interaction of the Co d orbitals with the bulk states of the Cu(111) surface, a proper description of the contribution given by the coupling with the localized surface states to the Anderson widths is crucial to describe the interference line shape. We find that the coupling of the Co 4s orbital with the Shockley surface states is responsible of two main features observed in the measured conductance spectra, the dip shape around the Fermi energy and the resonance structure at the surface state low band edge.

Iron phthalocyanine on Au(111) is a "non-Landau" Fermi liquid

“…The resulting Kondo temperatures are T The s-like orbitals of the STM tip have a larger overlap with the 3z 2 − r 2 orbital of FePc than with the molecular π orbitals and the substrate conduction-band wave functions. Ab initio calculations for Co on Cu(111) confirm this picture [64]. For this reason, the dominant contribution to the experimental dI/dV spectra corresponds to the spectral density ρ 1 (ω) = ρ 1↑ (ω) + ρ 1↓ (ω) in channel τ = 1.…”

“…With a single set of parameters we explained three key experiments on the differential conductance of this system [1,2,19]. The sole assumption (i.e., that the scanning tunneling microscope senses mainly the 3d orbital of Fe with 3d 2 − r 2 symmetry) is simple, physically realistic, and consistent with ab initio calculations [64] The same model also explains the recent experiments for MnPc on Au(111) [38], which exhibit a dependence on magnetic field with qualitative features similar to those in FePc on Au(111). Alternative explanations proposed for these experiments are questionable or contradict well established facts, like the role of Hund rules in defining ground-state multiplets.…”