Identification of Topological Surface State in PdTe2 Superconductor by Angle-Resolved Photoemission Spectroscopy
LIU Yan1, ZHAO Jian-Zhou1, YU Li1, LIN Cheng-Tian2, LIANG Ai-Ji1, HU Cheng1, DING Ying1, XU Yu1, HE Shao-Long1, ZHAO Lin1, LIU Guo-Dong1, DONG Xiao-Li1, ZHANG Jun1, CHEN Chuang-Tian3, XU Zu-Yan3, WENG Hong-Ming1,4, DAI Xi1,4, FANG Zhong1,4, ZHOU Xing-Jiang1,4*
1Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 2Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany 3Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 4Collaborative Innovation Center of Quantum Matter, Beijing 100871
High-resolution angle-resolved photoemission measurements are carried out on transition metal dichalcogenide PdTe2 that is a superconductor with a Tc at 1.7 K. Combined with theoretical calculations, we discover for the first time the existence of topologically nontrivial surface state with Dirac cone in PbTe2 superconductor. It is located at the Brillouin zone center and possesses helical spin texture. Distinct from the usual three-dimensional topological insulators where the Dirac cone of the surface state lies at the Fermi level, the Dirac point of the surface state in PdTe2 lies deeply below the Fermi level at ∼1.75 eV binding energy and is well separated from the bulk states. The identification of topological surface state in PdTe2 superconductor deeply below the Fermi level provides a unique system to explore new phenomena and properties and opens a door for finding new topological materials in transition metal chalcogenides.
2015, Vol. 32 
