Bi2Te1.6S1.4 - a Topological Insulator in the Tetradymite Family

Abstract

We describe the crystal growth, crystal structure, and basic electrical properties of Bi2Te1.6S1.4, which incorporates both S and Te in its Tetradymite quintuple layers in the motif -[Te0.8S0.2]-Bi-S-Bi-[Te0.8S0.2]-. This material differs from other Tetradymites studied as topological insulators due to the increased ionic character that arises from its significant S content. Bi2Te1.6S1.4 forms high quality crystals from the melt and is the S-rich limit of the ternary Bi-Te-S γ-Tetradymite phase at the melting point. The native material is n-type with a low resistivity; Sb substitution, with adjustment of the Te to S ratio, results in a crossover to p-type and resistive behavior at low temperatures. Angle resolved photoemission study shows that topological surface states are present, with the Dirac point more exposed than it is in Bi2Te3 and similar to that seen in Bi2Te2Se. Single crystal structure determination indicates that the S in the outer chalcogen layers is closer to the Bi than the Te, and therefore that the layers supporting the surface states are corrugated on the atomic scale.

To be published in Physical Review B Rapid Communications 16 douuble spaced pages. 4 figures 1 table

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• Gigantic surface life-time of an intrinsic topological insulator revealed via time-resolved (pump-probe) ARPES
• Topological insulator in a Bi-Bi${}_2$Se${}_3$ infinitely adaptive superlattice phase
• Oscillatory surface dichroism of an insulating topological insulator Bi2Te2Se
• Artificial Intelligence for High-Throughput Discovery of Topological Insulators: the Example of Alloyed Tetradymites
• Understanding Bulk Defects in Topological Insulators from Nuclear-Spin Interactions
• Three-dimensional topological insulators: A review on host materials
• A strong-topological-metal material with multiple Dirac cones
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• Kondo screening by the surface modes of a strong topological insulator
• Observation of anisotropic Dirac cones in the topological material Ti2Te2P
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• Preferential site ordering alters the magnetic structure of Sm${}_3$Ru${}_4$Sn${}_{13-x}$Ge${}_x$ ($x=0$-2)