Multiband quasiparticle interference in the topological insulator   Cu_(x)Bi_(2)Te_(3)
  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. 
E. van Heumen, G.A.R. van Dalum, J. Kaas, N. de Jong, J. Oen, Y.K.   Huang, A.K. Mitchell, L. Fritz, M.S. Golden
cond-mat.mes-hall cond-mat.mtrl-sci cond-mat.str-el