Prediction of van Hove singularity and magnetic phase transition in monolayer ReX₂ (X = S, Se, or Te)

Ina Marie R. Verzola^1*, Rovi Angelo B. Villaos¹, Zhi-Quan Huang¹, Chia-Hsiu Hsu^1,2, Hsin Lin³, Feng-Chuan Chuang^1,2,4

¹Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
²Physics Division, National Center for Theoretical Sciences, Taipei, Taiwan
³Institute of Physics, Academia Sinica, Taipei, Taiwan
⁴Department of Physics, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Ina Marie R. Verzola, email:irverzola@g-mail.nsysu.edu.tw

Through systematic first-principles calculations, the structural, electronic, magnetic, and topological properties of rhenium-based transition metal dichalcogenides were studied. Formation energy calculations showed that the bulk and monolayer ReX₂ exhibit the 1T” structure. Phonon dispersion calculations further confirmed the thermodynamic stability of the monolayer 1T” ReX₂. Moreover, van Hove singularity (vHs) is observed in monolayer ReS₂ and ReTe₂ suggesting possible superconductivity. Focusing on the monolayer phases, two-sided hydrogenation caused a stable structural phase transition from 1T” to 1T. Furthermore, a ferromagnetic phase transition was observed on ReS₂H₂ and ReSe₂H from their corresponding non-magnetic pristine cases. Finally, ReTe₂H exhibited non-trivial topological property as confirmed by the calculated Z₂ topological invariance number. Results show that the ReX₂ monolayers have tunable electronic, magnetic, and topological properties which have the potential for spintronics applications.

Keywords: 2D magnetic materials, rhenium transition metal dichalcogenides, first-principles calculations, van Hove singularity