Searching for a promising topological Dirac nodal-line semimetal by angle resolved photoemission spectroscopy

Topological semimetals, in which conduction and valence bands cross each other at either discrete points or along a closed loop with symmetry protected in the momentum space, exhibited great potential in applications of optical devices as well as heterogeneous catalysts or antiferromagnetic spintronics, especially when the crossing points/lines matches Fermi level (EF). It is intriguing to find the “ideal” topological semimetal material, in which has a band structure with Dirac band-crossing located at EF without intersected by other extraneous bands. Here, by using angle resolved photoemission spectroscopy (ARPES), we investigate the band structure of the so-called “square-net” topological material ZrGeS. The Brillouin zone (BZ) mapping shows the Fermi surface (FS) of ZrGeS is composed by a diamond-shaped nodal line loop at the center of BZ and small electron-like Fermi pockets around X point. The Dirac nodal line band-crossing located right at EF, and shows clearly the linear Dirac band dispersions within a large energy range >1.5 eV below EF, without intersected with other bands. The obtained Fermi velocities and effective masses along Γ-X, Γ-M and M-X high symmetry directions were 4.5 ~ 5.9 eV•Å and 0 ~ 0.50 me, revealing an anisotropic electronic property. Our results suggest that ZrGeS, as a promising topological nodal line semimetal (TNLSM), could provide a promising platform to investigate the Dirac-fermions related physics and the applications of topological devising.