Role of surface states in STM spectroscopy of (111) metal surfaces with Kondo adsorbates

TL;DR

This paper uses a nearly-free-electron model to analyze how surface states influence STM spectroscopy of (111) metal surfaces with Kondo impurities, revealing substrate-dependent effects on conductance and line shapes.

Contribution

It introduces a model highlighting the significant role of surface states in STM spectra of (111) metal surfaces with Kondo adsorbates, explaining substrate differences.

Findings

Surface states significantly affect conductance in Cu(111) and Au(111).

Differences in line shapes are due to surface band positions relative to Fermi energy.

Lateral dependence of line shape amplitude transitions from bulk-like to surface-like.

Abstract

A nearly-free-electron (NFE) model to describe STM spectroscopy of (111) metal surfaces with Kondo impurities is presented. Surface states are found to play an important role giving a larger contribution to the conductance in the case of Cu(111) and Au(111) than Ag(111) surfaces. This difference arises from the farther extension of the Ag(111) surface state into the substrate. The different line shapes observed when Co is adsorbed on different substrates can be explained from the position of the surface band onset relative to the Fermi energy. The lateral dependence of the line shape amplitude is found to be bulk-like for R|| < 4 Amstrongs and surface-like at larger distances, in agreement with experimental data.