Evidence of Dirac cones with 3D character probed by dHvA oscillations in nodal-line semimetal ZrSiS

Abstract

The topological quantum materials, including Dirac and Weyl semimetals, represent a new class of quantum materials with symmetry-protected band touching points. The essential properties of Dirac/Weyl fermions, including light effect mass, high mobility and non-trivial Berry phase, can be revealed by quantum oscillations. Here we present the first systematic de Haas–van Alphen (dHvA) oscillation studies on the recently discovered Dirac line-node semimetal ZrSiS a new type of topological phase of mater with Dirac crossings along a one dimensional line. In contrast with the recently-reported weak Shubnikov-de Haas oscillations which attenuate quickly when the field is rotated close to the ab-plane, the dHvA oscillations in ZrSiS were found to be strong under arbitrary field orientations, enabling us to explore not only the intrinsic properties of Dirac fermions but also the dimensionality of Fermi surface consisting of Dirac line node. Our experiments not only reveal evidence of Dirac fermions from multiple Dirac bands, but also show the Fermi surface enclosing the Dirac nodal line is of three-dimensional character for the first time. Furthermore, we observed surprisingly strong Zeeman splitting in the dHvA oscillations related to a small Fermi surface with a two-dimensional character. These results shed light on the nature of the line-node Dirac state of ZrSiS.