Topological Nodal Line Semimetal in Non-Centrosymmetric PbTaS**Supported by the National Natural Science Foundation of China under Grant No 11504366, and the National Basic Research Program of China under Grant Nos 2015CB921503 and 2016YFE0110000.

Abstract

Topological semimetals are a new type of matter with one-dimensional Fermi lines or zero-dimensional Weyl or Dirac points in momentum space. Here using first-principles calculations, we find that the non-centrosymmetric PbTaS is a topological nodal line semimetal. In the absence of spin-orbit coupling (SOC), one band inversion happens around a high symmetrical point, which leads to forming a nodal line. The nodal line is robust and protected against gap opening by mirror reflection symmetry even with the inclusion of strong SOC. In addition, it also hosts exotic drumhead surface states either inside or outside the projected nodal ring depending on surface termination. The robust bulk nodal lines and drumhead-like surface states with SOC in PbTaS make it a potential candidate material for exploring the freakish properties of the topological nodal line fermions in condensed matter systems.