Direct Observation of the Topological Surface States in Lead-Based Ternary Telluride Pb(Bi1-xSbx)2Te4

TL;DR

This study experimentally confirms the existence of topological surface states in Pb(Bi1-xSbx)2Te4, a lead-based ternary telluride, demonstrating its potential as a tunable three-dimensional topological insulator with variable Dirac carriers.

Contribution

First direct observation of topological surface states in Pb(Bi1-xSbx)2Te4, revealing its strong topological insulator nature and tunable Dirac carrier type via Sb substitution.

Findings

Identified a topological surface state with a hexagonally deformed Dirac cone.

Observed a change in Dirac carrier type from n-type to p-type with Sb substitution.

Pb(Bi1-xSbx)2Te4 is a promising platform for exploring topological phenomena.

Abstract

We have performed angle-resolved photoemission spectroscopy on Pb(Bi1-xSbx)2Te4, which is a member of lead-based ternary tellurides and has been theoretically proposed as a candidate for a new class of three-dimensional topological insulators (TIs). In PbBi2Te4, we found a topological surface state with a hexagonally deformed Dirac-cone band dispersion, indicating that this material is a strong TI with a single topological surface state at the Brillouin-zone center. Partial replacement of Bi with Sb causes a marked change in the Dirac carrier concentration, leading to the sign change of Dirac carriers from n-type to p-type. The Pb(Bi1-xSbx)2Te4 system with tunable Dirac carriers thus provides a new platform for investigating exotic topological phenomena.