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

摘要

Using low temperature scanning tunneling spectroscopy, we probe the Landaulevels of the topologically protected state of Sb2Te3(0001) after in-situcleavage of a single crystal. Landau levels are visible for magnetic fields B >2 T at energies, which confirm the Dirac type dispersion including the zerothLandau level. We find different Dirac velocities for the lower and the upperpart of the Dirac cone in reasonable agreement with previous density functionaltheory data. The Dirac point deduced from the zeroth Landau level shifts byabout 40 meV between different areas of the sample indicating long rangepotential fluctuations. The local potentials are correlated to different localdefect densities varying slightly stronger than expected from a statisticaldistribution. The quasiparticle lifetime deduced from the width of the Landaulevel peaks decreases close to inversely with the electron energy with respectto the Fermi level. Consequently, we attribute the peak width to a dominatingscattering of the hot quasiparticles by electron-electron interaction.