A Non-equilibrium STM model for Kondo Resonance on surface

TL;DR

This paper develops a self-consistent non-equilibrium STM model to study how energy range and cutoff influence Kondo resonance shapes in tunneling spectra, revealing Fano line shapes due to electron energy filtering.

Contribution

It introduces a novel self-consistent non-equilibrium Green function approach to model Kondo resonance in STM measurements, emphasizing the impact of energy cutoff and window on spectral features.

Findings

Energy cutoff causes a transition from peak to Fano line shape in spectra.

High-energy electron removal introduces dip structures in Kondo resonance.

The model aligns with Tersoff theory when no energy cutoff is applied.

Abstract

Based on a no-equilibrium STM model, we study Kondo resonance on a surface by self-consistent calculations. The shapes of tunneling spectra are dependent on the energy range of tunneling electrons. Our results show that both energy-cutoff and energy-window of tunneling electrons have significant influence on the shapes of tunneling spectra. If no energy-cutoff is used, the Kondo resonances in tunneling spectrum are peaks with the same shapes in the density of state of absorbed magnetic atoms. This is just the prediction of Tersoff theory. If we use an energy cutoff to remove high-energy lectrons, a dip structure will modulate the Kondo resonance peak in the tunneling spectrum. The real shape of Kondo peak is the mixing of the peak and dip, the so-called Fano line shape. The method of self-consistent non-equilibrium matrix Green function is discussed in details.