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arXiv · 1006.3843

Observation of Single Dirac Cone Topological Surface State in Compounds TlBiTe2 and TlBiSe2 from a New Topological Insulator Family

Yulin Chen·Zhongkai Liu·James G. Analytis·Jiun-Haw Chu·Haijun Zhang·Sung-Kwan Mo·Robert G. Moore·Donghui Lu·Ian Fisher·Shoucheng Zhang·Zahid Hussain·Z. -X. Shen
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Abstract

Angle resolved photoemission spectroscopy (ARPES) studies were performed on two compounds (TlBiTe$_2$ and TlBiSe$_2$) from a recently proposed three dimensional topological insulator family in Thallium-based III-V-VI$_2$ ternary chalcogenides. For both materials, we show that the electronic band structures are in broad agreement with the $ab$ $initio$ calculations; by surveying over the entire surface Brillouin zone (BZ), we demonstrate that there is a single Dirac cone reside at the center of BZ, indicating its topological non-triviality. For TlBiSe$_2$, the observed Dirac point resides at the top of the bulk valance band, making it a large gap ($\geq$200$meV$) topological insulator; while for TlBiTe$_2$, we found there exist a negative indirect gap between the bulk conduction band at $M$ point and the bulk valance band near $Γ$, making it a semi-metal at proper doping. Interestingly, the unique band structures of TlBiTe$_2$ we observed further suggest TlBiTe$_2$ may be a candidate for topological superconductors.

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Yulin Chen, Zhongkai Liu, James G. Analytis, Jiun-Haw Chu, Haijun Zhang, Sung-Kwan Mo, Robert G. Moore, Donghui Lu, Ian Fisher, Shoucheng Zhang, Zahid Hussain, Z. -X. Shen. 2010-06-19. Observation of Single Dirac Cone Topological Surface State in Compounds TlBiTe2 and TlBiSe2 from a New Topological Insulator Family. https://doi.org/10.1103/physrevlett.105.266401

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