Prediction of the topologically nontrivial phase in three-dimensional ABX Zintl compounds

Ina Marie R. Verzola^1*, Rovi Angelo B. Villaos¹, Zhi-Quan Huang¹, Hsin Lin², Feng-Chuan Chuang^1,3,4,5

¹Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
²Institute of Physics, Academia Sinica, Taipei, Taiwan
³Physics Division, National Center for Theoretical Sciences, Taipei, Taiwan
⁴Center for Theoretical and Computational Physics, National Sun Yat-sen University, Kaohsiung, Kaohsiung, Taiwan
⁵Department of Physics, National Tsing Hua University, Hsinchu, Taiwan

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

Zintl compounds have garnered research interest due to their diverse technological applications. Utilizing first-principles calculations, we performed a systematic study on ABX (A = Li, Na, K, Rb, or Cs; B = Si, Ge, Sn, or Pb; and X = P, As, Sb, or Bi) Zintl materials with 𝑃6₃𝑚𝑐 KSnSb-type structure. Notably, six ABX Zintl compounds (RbSiBi, CsSiBi, LiGeBi, KGeBi, RbGeBi, and CsGeBi) are found to have topologically nontrivial phases, as confirmed by the calculated Z₂ invariant under the hybrid functional approach. The topological phase transition was driven by spin-orbit coupling, as demonstrated for the representative material, CsGeBi. The nontrivial topological phase was further confirmed by the presence of gapless surface states. Finally, phonon dispersion and ab initio molecular dynamics confirm the thermodynamic stability of CsGeBi. These results provide foundational insights that could drive further experimental research and synthesis of ABX Zintl compounds.

Keywords: Topological insulators, First-principles calculation, ABX Zintl compounds, Three-dimensional compounds, Spin-orbit coupling