Magneto-Transport and High-Resolution Angle-Resolved Photoelectron Spectroscopy Studies of Palladium Doped Bi$_{2}$Te$_{3}$

TL;DR

This study investigates the effects of palladium doping on Bi2Te3 topological insulators using magneto-transport and ARPES, revealing changes in electronic properties, surface states, and carrier types.

Contribution

It provides new insights into how Pd doping modifies the electronic structure and surface states of Bi2Te3, including shifts in the Dirac point and carrier type crossover.

Findings

High magnetoresistance (~1500%) and mobility (~93000 cm^2V^{-1}s^{-1}) in pristine Bi2Te3.

Detection of Shubnikov-de Haas oscillations indicating 2D topological surface states.

Transition from n-type to p-type carriers with Pd doping.

Abstract

We have performed magneto-transport and high-resolution angle-resolved photoelectron spectroscopy (ARPES) measurements on palladium (Pd) doped topological insulator Pd$_{x}$Bi$_{2}$Te$_{3}$ (0 $\leq$ x $\leq$ 0.20) single crystals. We have observed unusually high values of magnetoresistance ($\sim$ 1500%) and mobility ($\sim$ 93000 cm$^{2}$V$^{-1}$s$^{-1}$) at low temperatures 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$_{2}$Te$_{3}$ to p-type charge carriers upon Pd doping. The ARPES measurements show that the conduction band crosses the Fermi level for pristine Bi$_{2}$Te$_{3}$, 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 $\sim$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.