Chemical tuning of electronic and transport properties of the Bi-Se-Te family of topological insulators

Abstract

We use laser-based Angle-Resolved Photoemission Spectroscopy (ARPES) to study how chemical substitution modifies the electronic properties of the Bi2(Se{1-x}Tex)3 (BiSeTe) family of topological insulators. We find that increasing the Te content lowers the chemical potential, leading to a decrease in the binding energy of the Dirac point and a reduction in the density of states originating from the bulk band. This reduction leads to a transition from metallic to semiconducting temperature dependence of the resistivity. For the highest Te concentration, the resistivity nearly saturates at the lowest temperatures. The presence of this plateau indicates that metallic topological surface states dominate the conductance, opening the possibility of studying their transport properties.

Figures (6)

• Figure 1: Fermi surface (a-c) and band dispersion (d-f) of BiSeTe for few Te concentrations as indicated above panels. An arrow in panel (d) points to intensity from the bulk band for the lowest Te concentration.
• Figure 2: (a) Energy distribution curves showing the decrease of binding energy of Dirac point with increasing Te concentration. (b) Energy of the Dirac point as a function of Te content extracted by fitting peak positions in (a). (c) Fermi caliper size extracted from Fig. 1.
• Figure 3: Illustration of small differences in band dispersion for crystals from the same batch. a-b) for 24 % Te content, c-d) for 40 % Te content, e-f) for 50 % Te content
• Figure 4: Momentum distribution curves of the surface state bands extracted at the chemical potential. a) for negative momenta. b) for positive momenta.
• Figure 5: Full-width at half-maximum (FWHM) of the MDC peaks as a function of binding energy, extracted from Lorentzian fits. a) for 24 % Te content, b) for 40 % Te content, c) for 50 % Te content