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et al. ; Spin polarization of a topological surface state for GeBi 2Te 4, the newly discovered three-dimensional topological insulator, has been studied by means of state-of-the-art spin- and angle-resolved photoemission spectroscopy. It has been revealed that the disorder in the crystal has a minor effect on the surface-state spin polarization, which is 70% near the Dirac point in the bulk energy gap region (∼180 meV). This finding promises not only to realize a highly spin-polarized surface-isolated transport but also to add functionality to its thermoelectric and thermomagnetic properties. © 2012 American Physical Society. ; This work was financially supported by Grant-in-Aid for Scientific Research Kiban A (Grant No. 23244066) and Kiban B (Grant No. 23340105) of the Japan Society for the Promotion of Science (JSPS). We also acknowledge partial support from the Basque Country government, Departamento de Educación, Universidades e Investigación (Grant No. IT-366-07), and the Spanish Ministerio de Ciencia e Inovación (Grant No. FIS2010-19609-C02-00). ; Peer Reviewed

et al. ; The experimental evidence is presented of the topological insulator state in PbBi 2Te 4. A single surface Dirac cone is observed by angle-resolved photoemission spectroscopy with synchrotron radiation. Topological invariants Z 2 are calculated from the ab initio band structure to be 1;(111). The observed two-dimensional isoenergy contours in the bulk energy gap are found to be the largest among the known three-dimensional topological insulators. This opens a pathway to achieving a sufficiently large spin current density in future spintronic devices. © 2012 American Physical Society. ; This work was financially supported by KAKENHI (Grants No. 20340092 and No. 23340105), Grant-in-Aid for Scientific Research (B) of JSPS. We also acknowledge partial support by the Department of Education of the Basque Country Government, the University of the Basque Country (project GV-UPV/EHU, Grant No. IT-366-07), Ministerio de Ciencia e Inovación (Grant No. FIS2010-19609-C02-00). ; Peer Reviewed

We have grown the phase-homogeneous ternary compound with composition Bi2Te1.85S1.15 very close to the stoichiometric Bi2Te2S. The measurements performed with spin- and angle-resolved photoelectron spectroscopy as well as density functional theory and GW calculations revealed a wide-band-gap three-dimensional topological insulator phase. The surface electronic spectrum is characterized by the topological surface state (TSS) with Dirac point located above the valence band and Fermi level lying in the band gap. TSS band dispersion and constant energy contour manifest a weak warping effect near the Fermi level along with in-plane and out-of-plane spin polarization along the Γ-K̄ line. We identified four additional states at deeper binding energies with high in-plane spin polarization. ; We acknowledge partial support from the Saint Petersburg State University (Grant No. 15.61.202.2015), Tomsk State University competitiveness improvement program (Project No. 8.1.01.2017), and the Spanish Ministry of Science and Innovation (Grant No. FIS2016-75862-P). This study was partially supported by the Russian Science Foundation (Projects No. 17-12-01047, for the electrophysical properties, and No. 18-12-00169, for the theoretical calculations) and by the Russian Foundation for Basic Research (Project No. 17-08-00955, for the crystal growth and structural characterization). S.V.E. acknowledges support by the Fundamental Research Program of the State Academies of Sciences for 2013–2020. I.P.R. acknowledges support by the Ministry of Education and Science of the Russian Federation within the framework of the governmental program Megagrants (state task No. 3.8895.2017/P220). A.K. was financially supported by KAKENHI Grants No. 26247064 and No. 17H06138. ; Peer Reviewed