Predicting topological phases in hydrogenated transition metal dichalcogenide monolayers: A first-principles study

Liang-Ying Feng^1*, Harvey N. Cruzado¹, Rovi Angelo B. Villaos¹, Zhi-Quan Huang¹, Hung-Chung Hsueh², Hsin Lin³, Feng-Chuan Chuang¹

¹Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan
²Department of Physics, Tamkang University, Taipei, Taiwan
³Institute of Physics, Academia Sinica, Taipei, Taiwan

* Presenter:Liang-Ying Feng, email:zxc6981189@g-mail.nsysu.edu.tw

Two dimensional (2D) transition metal dichalcogenides (TMDs) monolayers have currently been of immense interest in materials research because of their versatility and tunable electronic properties. In this study, we perform systematically the first-principles calculations of possible topological phases on 1T and 2H MX2 monolayers, as well as the effects of hydrogenation on one or both sides of the films. With regards to structural stability, we find that Group IV(Ti, Zr, Hf)-, VI(Cr, Mo, W)-, and X(Ni, Pd, Pt)-based TMDs, respectively, adopted 1T, 2H, and 1T as their stable structures for unhydrogenated cases. However, upon hydrogenation, we observe structural phase transition from 1T to 2H for Group IV, and from 2H to 1T for Group VI, and no transition was observed for Group X. We find that for the stable structures, 2H HfTe2 with 1 hydrogen, 1T CrTe2 with 2 hydrogen, and 1T PtSe2 with 1 hydrogen, are 2D metallic which have the non-trivial band topology; while the unstable structure 2H PdSe2 without hydrogen is identified to be a topological insulator with large band gap of 0.23eV. These findings show that these TMDs have the potential for spintronics applications.

Keywords: 2D materials, transition metal dichalcogenides, topological insulator, first-principles calculation