Revisiting the Topological Nature of TaIrTe4, SrSi2, and Cu2XY3: An ab-initio Investigation

Abstract

Several topological electronic materials have been theoretically predicted, leading to a comprehensive catalog systematically characterized by their band crossings. Researchers have attempted to experimentally verify the topological nature of some materials from the present catalogs, but not all efforts have yielded positive results. Here, we introduce a possible reason for the discrepancies between theoretical and experimental results. In this direction, firstly we have revisited the nature of the well-known topological materials TaIrTe$_4$ and SrSi$_2$ using \textit{state-of-the-art ab-initio} calculations, and found additional Weyl points in both materials that were missing in previously reported studies. Then we have verified the recently predicted topological states of the \textit{Imm2}-phase of Cu$_2$XY$_3$ (X=Si, Ge, Sn \& Y=S, Se, Te). Contrary to previously reported results, we did not find any Weyl points or nodal arcs in Cu$_2$SnTe$_3$. Notably, our theoretical results reveal that Cu$_2$SiTe$_3$, Cu$_2$GeTe$_3$ and Cu$_2$GeSe$_3$ each host four small nodal rings, eight Weyl points, and eight nodal arcs, respectively, which differ from previous studies. Considering Cu$_2$SnS$_3$ as an example, we have also investigated the robustness of the topological phase against local strain. Our study provides insights into the inconsistencies between theoretical predictions and experimental results, and demonstrates how the topological phase is sensitive to changes in lattice parameters, atomic positions, and exchange-correlation functionals.