Ni-Intercalation-Induced Topological Nodal Line States and Superconductivity in NiTe

Based on symmetry analyses and first-principles calculations, we report the predictions of topological fermions and superconductivity in Ni-intercalated transition metal chalcogenide NiTe. The self-intercalation of Ni introduces nonsymmorphic symmetry operations, protecting a pair of Dirac points and three intersecting Dirac nodal lines near Fermi energy level (EF), which generate spin-textured surface states across EF. Moreover, the Ni-intercalation strongly enhances electron-phonon coupling in NiTe and makes it an anisotropic Bardeen-Cooper-Schrieffer superconductor with a full superconducting gap and a critical temperature Tc similar to 1.5 K. The coexistence of topological surface states and superconductivity implies that NiTe is a potential material platform for exploring topological superconductivity.