Kondo effect on the surface of 3D topological insulators: Signatures in scanning tunneling spectroscopy

TL;DR

This paper studies how magnetic impurities on 3D topological insulator surfaces exhibit the Kondo effect, revealing distinctive signatures in scanning tunneling spectroscopy that differentiate them from non-magnetic impurities.

Contribution

It provides a detailed analysis of the Kondo effect signatures in quasiparticle interference patterns on topological insulator surfaces, incorporating energy dependence and surface warping effects.

Findings

Universal low-energy QPI signature of Kondo physics

Distinct spectral features from non-magnetic impurities

Agreement with recent experimental observations

Abstract

We investigate the scattering off dilute magnetic impurities placed on the surface of three-dimensional topological insulators. In the low-temperature limit, the impurity moments are Kondo-screened by the surface-state electrons, despite their exotic locking of spin and momentum. We determine signatures of the Kondo effect appearing in quasiparticle interference (QPI) patterns as recorded by scanning tunneling spectroscopy, taking into account the full energy dependence of the T matrix as well as the hexagonal warping of the surface Dirac cones. We identify a universal energy dependence of the QPI signal at low scanning energies as the fingerprint of Kondo physics, markedly different from the signal due to non-magnetic or static magnetic impurities. Finally, we discuss our results in the context of recent experimental data.