A topological surface state that is protected physically under the Bi2Te3-like five-layer block has been revealed on the Pb-based topological insulator (TI) PbBi4Te7 by bulk sensitive angle-resolved photoelectron spectroscopy (ARPES). Furthermore, conservation of the spin polarization of the hidden topological surface states is directly confirmed by bulk-sensitive spin ARPES observation. This finding paves the way to realize the real spintronics devices by TIs that are operable in the real environment.
We report the observation of two-dimensional Shubnikov-de Haas (SdH) oscillations in the topological insulator Tl1−xBi1+xSe2. Hall effect measurements exhibited electron-hole inversion in samples with bulk insulating properties. The SdH oscillations accompanying the hole conduction yielded a large surface carrier density of ns = 5.1 × 10 12 /cm 2 , with the Landau-level fan diagram exhibiting the π Berry phase. These results showed the electron-hole reversibility around the in-gap Dirac point and the hole conduction on the surface Dirac cone without involving the bulk metallic conduction.PACS numbers: 73.25.+i, 72.20.My,
The surface termination of the promising topological insulator TlBiSe2 has been studied by surface and bulk sensitive probes. Our scanning tunneling microscopy has unmasked for the first time the unusual surface morphology of TlBiSe2 obtained by cleaving, where islands are formed by residual atoms on the cleaved plane. The chemical condition of these islands was identified using core-level spectroscopy. We observed thallium core-level spectra that are strongly deformed by a surface component in sharp contrast to the other elements. We propose a simple explanation for this behavior by assuming that the sample cleaving breaks the bonding between thallium and selenium atoms, leaving the thallium layer partially covering the selenium layer. These findings will assist the interpretation of future experimental and theoretical studies on this surface.
We report the electric transport study of the three-dimensional topological insulator TlBiSe2. We applied a newly developed analysis procedure and precisely determined two-carrier transport properties. Magnetotransport properties revealed a multicarrier conduction of high-and low-mobility electrons in the bulk, which was in qualitative agreement with angle-resolved photoemission results [K. Kuroda et al., Phys. Rev. Lett. 105, 146801 (2010)]. The temperature dependence of the Hall mobility was explained well with the conventional Bloch-Grüneisen formula and yielded the Debye temperature ΘD = 113 ± 14 K. The results indicate that the scattering of bulk electrons is dominated by acoustic phonons.
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