Kondo resonance line-shape of magnetic adatoms on decoupling layers

TL;DR

This paper demonstrates that the Kondo resonance line-shape of magnetic adatoms on decoupling layers can be accurately modeled using the universal spectral function, providing precise Kondo temperature measurements and insights into magnetic field effects.

Contribution

It introduces a detailed fitting method using the universal spectral function for Kondo resonances on decoupling layers, improving the accuracy of Kondo temperature determination and analyzing magnetic field effects.

Findings

Excellent fit of the spectral function to experimental data at zero field.

Reliable determination of Kondo temperature from zero-field data.

Ambiguous results at finite magnetic fields with two interpretations proposed.

Abstract

The zero-bias resonance in the dI/dV tunneling spectrum recorded using a scanning tunneling microscope above a spin-1/2 magnetic adatom (such as Ti) adsorbed on a decoupling layer on metal surface can be accurately fitted using the universal spectral function of the Kondo impurity model both at zero field and at finite external magnetic field. Excellent agreement is found both for the asymptotic low-energy part and for the high-energy logarithmic tails of the Kondo resonance. For finite magnetic field, the nonlinear fitting procedure consists in repeatedly solving the impurity model for different Zeeman energies in order to obtain accurate spectral functions which are compared with the experimental dI/dV curves. The experimental results at zero field are sufficiently restraining to enable an unprecedented reliability in the determination of the Kondo temperature, while at finite fields the results are more ambiguous and two different interpretations are proposed.