title: Single Dirac cone topological surface state and unusual thermoelectric property of compounds from a new topological insulator family.
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.
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Y L
authors.initials: YL
authors.lastname: Chen
authors.forename: Z K
authors.initials: ZK
authors.lastname: Liu
authors.forename: J G
authors.initials: JG
authors.lastname: Analytis
authors.forename: J-H
authors.initials: JH
authors.lastname: Chu
authors.forename: H J
authors.initials: HJ
authors.lastname: Zhang
authors.forename: B H
authors.initials: BH
authors.lastname: Yan
authors.forename: S-K
authors.initials: SK
authors.lastname: Mo
authors.forename: R G
authors.initials: RG
authors.lastname: Moore
authors.forename: D H
authors.initials: DH
authors.lastname: Lu
authors.forename: I R
authors.initials: IR
authors.lastname: Fisher
authors.forename: S C
authors.initials: SC
authors.lastname: Zhang
authors.forename: Z
authors.initials: Z
authors.lastname: Hussain
authors.forename: Z-X
authors.initials: ZX
authors.lastname: Shen