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New topological surface state in layered topological insulators: Unoccupied dirac cone |
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| Authors: | S. V. Eremeev I. V. Silkin T. V. Menshchikova A. P. Protogenov E. V. Chulkov |
| Affiliation: | 1. Institute of Strength Physics and Materials Science, Siberian Branch, Russian Academy of Sciences, Tomsk, 634021, Russia 2. Tomsk State University, Tomsk, 634050, Russia 3. Institute of Applied Physics, Russian Academy of Sciences, Nizhni Novgorod, 603950, Russia 4. Donostia International Physics Center, 20018 San Sebastián, Basque Country, Spain 5. Departamento de Física de Materiales UPV/EHU and Centro de Física de Materiales CFM and Centro Mixto CSIC-UPV/EHU, 20080 San Sebastián/Donostia, Basque Country, Spain |
| Abstract: | The unoccupied states in topological insulators Bi2Se3, PbSb2Te4, and Pb2Bi2Te2S3 are studied by the density functional theory methods. It is shown that a surface state with linear dispersion emerges in the inverted conduction band energy gap at the center of the surface Brillouin zone on the (0001) surface of these insulators. The alternative expression of ?2 invariant allowed us to show that a necessary condition for the existence of the second $bar Gamma $ Dirac cone is the presence of local gaps at the time reversal invariant momentum points of the bulk spectrum and change of parity in one of these points. |
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