The Kondo Resonance Line Shape in Scanning Tunnelling Spectroscopy: Instrumental Aspects

TL;DR

This paper investigates how instrumental factors like modulation voltage, noise, and temperature influence the observed Kondo resonance line shape in scanning tunnelling spectroscopy, complicating the extraction of intrinsic properties.

Contribution

It provides an analysis of instrumental broadening effects on Kondo resonance measurements using experimental data and modeling, highlighting challenges in accurately determining intrinsic line widths.

Findings

Instrumental broadening significantly affects Kondo resonance line shape.

Temperature variations complicate the extraction of intrinsic line width.

Modeling helps understand the influence of measurement parameters.

Abstract

In the scanning tunnelling microscope, the many-body Kondo effect leads to a zero-bias feature of the differential conductance spectra of magnetic adsorbates on surfaces. The intrinsic line shape of this Kondo resonance and its temperature dependence in principle contain valuable information. We use measurements on a molecular Kondo system, all-trans retinoic acid on Au(111), and model calculations to discuss the role of instrumental broadening. The modulation voltage used for the lock-in detection, noise on the sample voltage, and the temperature of the microscope tip are considered. These sources of broadening affect the apparent line shapes and render difficult a determination of the intrinsic line width, in particular when variable temperatures are involved.