Epitaxial growth and atomic-scale study of type-II Dirac semimetal 1T-NiTe2 film

By means of molecular beam epitaxy, x-ray diffraction, transmission electron microscopy, and in situ scanning tunneling microscopy, we successfully prepare type-II Dirac semimetal 1T -NiTe2 films and investigate their surface morphology, electronic structure, and topological characteristics on the atomic scale. Atomically flat NiTe2 films can be readily prepared on SrTiO3(001) substrates at similar to 210 degrees C. For NiTe2 multilayers (similar to 17 layers), the predominant surface defect is identified as intercalated Ni atoms inside the van der Waals gap. Besides, we observe spin-splitting and resonant topological surface states near EF and at similar to - 0.65 eV, respectively. They are suppressed at the step edges and in ultrathin monolayer and bilayer films. By exploring the quasiparticle interference, we visualize a backscattering suppression within 140 +/- 40 meV in multilayer NiTe2, which is associated possibly with the type-II Dirac node.