Single Dirac cone topological surface state and unusual thermoelectric property of compounds from a new topological insulator family |
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Authors: | Chen Y L Liu Z K Analytis J G Chu J-H Zhang H J Yan B H Mo S-K Moore R G Lu D H Fisher I R Zhang S C Hussain Z Shen Z-X |
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Institution: | Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA. |
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Abstract: | Angle resolved photoemission spectroscopy study on TlBiTe2 and TlBiSe2 from a thallium-based ternary chalcogenides family revealed a single surface Dirac cone at the center of the Brillouin zone for both compounds. For TlBiSe2, the large bulk gap (~200 meV) makes it a topological insulator with better mechanical properties than the previous binary 3D topological insualtor family. For TlBiTe2, the observed negative bulk gap indicates it as a semimetal, instead of a narrow-gap semiconductor as conventionally believed; this semimetality naturally explains its mysteriously small thermoelectric figure of merit comparing to other compounds in the family. Finally, the unique band structures of TlBiTe2 also suggest it as a candidate for topological superconductors. |
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