Quasiparticle interference from magnetic impurities

TL;DR

This paper investigates how magnetic impurities influence quasiparticle interference patterns observed via FT-STS, highlighting the effects of electronic correlations like the Kondo effect and limitations of the JDOS interpretation.

Contribution

It provides a detailed analysis of magnetic impurity effects on QPI, emphasizing the role of electronic correlations and challenging the adequacy of the JDOS approach.

Findings

Magnetic impurities cause significant QPI intensity enhancement due to the Kondo effect.

Electronic correlations lead to universal low-temperature QPI features.

JDOS interpretation often fails to accurately describe magnetic impurity-induced QPI.

Abstract

Fourier transform scanning tunneling spectroscopy (FT-STS) measures the scattering of conduction electrons from impurities and defects, giving information about the electronic structure of both the host material and adsorbed impurities. We interpret such FT-STS measurements in terms of the quasiparticle interference (QPI), investigating the QPI due to magnetic impurities adsorbed on a range of representative non-magnetic host surfaces, and contrasting with the case of a simple scalar impurity or point defect. We demonstrate how the electronic correlations present for magnetic impurities markedly affect the QPI, showing e.g. a large intensity enhancement due to the Kondo effect, and universality at low temperatures/scanning-energies. The commonly-used joint density of states (JDOS) interpretation of FT-STS measurements is also considered, and shown to be insuffcient in many cases, including that of magnetic impurities.