Quantum oscillation studies of topological semimetal candidate ZrGeM (M=S, Se, Te)

The WHM - type materials (W=Zr/Hf/La, H=Si/Ge/Sn/Sb, M=O/S/Se/Te) have been predicted to be a large pool of topological materials. These materials allow for fine tuning of spin-orbit coupling, lattice constant and structural dimensionality for various combinations of W, H and M elements, thus providing an excellent platform to study how these parameters' tuning affect topological semimetal state. In this work, we report the high field quantum oscillation studies on ZrGeM (M=S, Se, and Te). We have found the first experimental evidence for their theoretically-predicted topological semimetal states. From the angular dependence of quantum oscillation frequency, we have also studied the Fermi surface topologies of these materials. Moreover, we have compared Dirac electron behavior between the ZrGeM and ZrSiM systems, which reveals deep insights to the tuning of Dirac state by spin-orbit coupling and lattice constants in the WHM systems.