Nonsymmorphic P21/m-MoTe2: Novel 2D Topological Materials

Nonsymmorphic symmetries play a significant role in the emergence of topological nontrivial phases in some 2D materials. Herein, a new 2D material P21/m-MoTe2 with nontrivial topological properties and nonsymmorphic symmetries is proposed. With the help of first-principles calculations, it is found that it is dynamically stable, and has relatively high energetic stability. When spin-orbit coupling (SOC) is ignored, this material is a semimetal with two intersects appearing on the high-symmetry line Gamma-Y. Detailed symmetry analysis reveal that they are protected by the screw operator C similar to 2y. After SOC is turned on, it turns into a topological insulator with a global bandgap of 94 meV. The large gap ensures that the topological nontrivial phase is robust to an external perturbation. The discovery of nonsymmorphic P21/m-MoTe2 expands the family of transition metal dichalcogenides and provides a new platform to study topological phases in 2D nonsymmorphic materials.