Signatures of Fermi surface topology change in the nodal-line semimetal ZrSiSe1−xTex

The topological nodal-line semimetal (TNLS) $\mathrm{ZrSi}M$ $(M=\mathrm{S}, \mathrm{Se}, \mathrm{Te})$ is a promising platform to study the TNLS phase by tuning chalcogens. In this work, we study the evolution of the Fermi surface (FS) by tuning the Se/Te ratio in ${\mathrm{ZrSiSe}}_{1\ensuremath{-}x}{\mathrm{Te}}_{x}$ compounds. Transport properties and magnetometry results present signatures of Fermi surface topology change by the sudden changes in symmetry and carrier densities, as well as singularity of FSs at the critical chemical potentials. A $2\frac{1}{2}$-order Lifshitz transition occurs when 0.20 $\ensuremath{\le}\phantom{\rule{4pt}{0ex}}x\phantom{\rule{4pt}{0ex}}\ensuremath{\le}$ 0.33. Another $3\frac{1}{2}$-order electron topological transition is revealed by a large diamagnetic anomaly of susceptibility at $x\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}$ 0.80. In combination with first-principles calculations, this study reveals the vital roles of spin-orbit coupling, charge transfer, and shifts of the chemical potential in the evolution of FSs in this system. Our results demonstrate how the FSs evolve in ${\mathrm{ZrSiSe}}_{1\ensuremath{-}x}{\mathrm{Te}}_{x}$ compounds, providing fundamental clues for designing topological state switchable devices.