Multiband quasiparticle interference in the topological insulator Cu_(x)Bi_(2)Te_(3)

TL;DR

This study investigates quasiparticle interference in Cu-doped Bi2Te3 using experimental techniques and theoretical modeling, revealing multiple scattering channels and the influence of defect types on surface state scattering.

Contribution

The paper identifies two new scattering channels in the topological insulator Cu0.2Bi2Te3 and models the scattering potential considering defect types, advancing understanding of quasiparticle behavior.

Findings

Three distinct energy windows for quasiparticle scattering.

Identification of two new scattering channels involving surface and conduction band states.

Real space density modulation exhibits three-fold symmetry influenced by defect types.

Abstract

We present angle resolved photoemission experiments and scanning tunneling spectroscopy results on the doped topological insulator Cu0.2Bi2Te3. Quasi-particle interference (QPI) measurements, based on high resolution conductance maps of the local density of states show that there are three distinct energy windows for quasi-particle scattering. Using a model Hamiltonian for this system two new scattering channels are identified: the first between the surface states and the conduction band and the second between conduction band states. We also observe that the real space density modulation has a predominant three-fold symmetry, which rules out a simple, isotropic impurity potential. We obtain agreement between experiment and theory by considering a modified scattering potential that is consistent with having mostly Bi-Te anti-site defects as scatterers.