Spatially resolved Landau level spectroscopy of the topological Dirac cone of bulk-type Sb2Te3(0001): potential fluctuations and quasiparticle lifetime

TL;DR

This study uses low temperature scanning tunneling spectroscopy to analyze Landau levels in Sb2Te3(0001), revealing Dirac dispersion, potential fluctuations, and quasiparticle lifetimes, which enhance understanding of topological surface states.

Contribution

It provides the first detailed Landau level spectroscopy of Sb2Te3(0001), identifying potential fluctuations and quasiparticle scattering mechanisms in topological surface states.

Findings

Landau levels confirm Dirac dispersion with a zeroth level.

Potential fluctuations of about 40 meV are observed across the sample.

Quasiparticle lifetime decreases inversely with energy, indicating electron-electron interactions.

Abstract

Using low temperature scanning tunneling spectroscopy, we probe the Landau levels of the topologically protected state of Sb2Te3(0001) after in-situ cleavage of a single crystal. Landau levels are visible for magnetic fields B > 2 T at energies, which confirm the Dirac type dispersion including the zeroth Landau level. We find different Dirac velocities for the lower and the upper part of the Dirac cone in reasonable agreement with previous density functional theory data. The Dirac point deduced from the zeroth Landau level shifts by about 40 meV between different areas of the sample indicating long range potential fluctuations. The local potentials are correlated to different local defect densities varying slightly stronger than expected from a statistical distribution. The quasiparticle lifetime deduced from the width of the Landau level peaks decreases close to inversely with the electron energy with respect to the Fermi level. Consequently, we attribute the peak width to a dominating scattering of the hot quasiparticles by electron-electron interaction.