Tunability of the topological nodal-line semimetal phase in ZrSiX-type materials*

The discovery of a topological nodal-line (TNL) semimetal phase in ZrSiS has invigorated the study of other members of this family. Here, we use angle-resolved photoemission spectroscopy (ARPES) to study the comparative electronic structure of ZrSiX (where X $=$ S, Se, Te) materials. Our experimental data and first-principles calculations, for the first time, reveal the tunability of topological nodal-line fermion phase in ZrSiX materials by changing the spin-orbit coupling strength via X-anion. Our findings establish a new material system with an SOC tunable nodal-line phase.