Magneto-Transport and High-Resolution Angle-Resolved Photoelectron Spectroscopy Studies of Palladium Doped Bi_2Te_3

We have performed magneto-transport and high-resolution angle-resolved photoelectron spectroscopy (ARPES) measurements on palladium (Pd) doped topological insulator Pd_xBi_2Te_3 (0 ≤ x ≤ 0.20) single crystals. We have observed unusually high values of magnetoresistance (∼ 1500 for pristine Bi2Te3 that decrease on Pd doping. The Shubnikov-de Haas (SdH) oscillations have been detected for x = 0.05, 0.10, confirming the presence of 2D topological surface states (TSSs) for these samples. The Hall measurement shows the crossover from n-type charge carriers in pristine Bi_2Te_3 to p-type charge carriers upon Pd doping. The ARPES measurements show that the conduction band crosses the Fermi level for pristine Bi_2Te_3, and the Dirac point of the TSSs and bulk-derived valence bands indicated shift to lower binding energy upon Pd doping in a rigid-band-like way up to x ∼0.10. Based on the comparison of the parameters obtained from the SdH and ARPES measurements, the reduction in the kF value in the magneto-transport measurements likely due to the band bending induced by the Schottky barrier.