Topological Dirac semimetal phase in Heusler-type Li₂YZ (Y = Zn or Cd; and Z = Ge, Sn, or Pb) compounds: A first-principles investigation

FAREEHA WAHEED^1*, Ina Marie R. Verzola¹, P C Sreeparvathy^1,2, Rovi Angelo B. Villaos¹, Zhi-Quan Huang¹, Feng-Chuan Chuang^1,2,3,5

¹Physics, Natonal Sun Yat-Sen University, Kaohsiung, Taiwan
²Physics Division, National Center for Theoretical SciencesSciences, Taipei 10617, Taiwan
³Center for Theoretical and Computational Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan
⁴Institute of Physics, Academia Sinica, Taipei, 115201, Taiwan
⁵Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan

* Presenter:FAREEHA WAHEED, email:waheedfareeha978@gmail.com

The search for stable Dirac semimetals with intriguing topological surface states is still gaining recognition in condensed matter research, as they offer potential technological applications. In this study, we propose the potential Dirac semimetal phase in Heusler-type Li₂YZ (Y = Zn or Cd; and Z = Ge, Sn, or Pb) compounds via first-principles calculations. Structural, electronic, and topological properties of Li₂YZ (Y = Zn or Cd; and Z = Ge, Sn, or Pb) compounds were studied by taking Li₂CdGe and Li₂CdPb as candidate materials. Our calculations revealed a symmetry-protected triple point phase in Li₂CdGe and Li₂CdPb without spin-orbit coupling (SOC) at the Γ high-symmetry point. Interestingly, the SOC induces a four-fold Dirac node phase in the bulk at the high-symmetry point. Remarkably, the Dirac node in Li₂CdGe is characterized by intriguing surface states and extended Fermi arcs on the (001) surface of the Brillouin zone. These results pave the way for further experimental studies to explore novel Dirac features in topological materials.

Keywords: Topological Dirac semimetals, Dirac node, Triple point, Topological surface states, High-symmetry point semimetal