High resolution angle-resolved photoemission measurements have been carried out on transition metal dichalcogenide PdTe2 that is a superconductor with a Tc at 1.7 K. Combined with theoretical calculations, we have discovered 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 deep 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 deep below the Fermi level provides a unique system to explore for new phenomena and properties and opens a door for finding new topological materials in transition metal chalcogenides.
@article{arxiv.1505.06642,
title = {Identification of Topological Surface State in PdTe2 Superconductor by Angle-Resolved Photoemission Spectroscopy},
author = {Yan Liu and Jianzhou Zhao and Li Yu and Chengtian Lin and Aiji Liang and Cheng Hu and Ying Ding and Yu Xu and Shaolong He and Lin Zhao and Guodong Liu and Xiaoli Dong and Jun Zhang and Chuangtian Chen and Zuyan Xu and Hongming Weng and Xi Dai and Zhong Fang and X. J. Zhou},
journal= {arXiv preprint arXiv:1505.06642},
year = {2015}
}