Strong anisotropic nodal lines in the TiBe family

Using first-principles calculations and k·p model analysis, we find that Dirac nodal lines (DNLs) exist in low energy band structures of real materials of the body-centered cubic TiBe family. The nodal lines are protected by mirror reflection symmetries of the systems. The anisotropic electronic state interaction around the Fermi level produces a strong anisotropic quasi-square shape nodal line in the systems. Moreover, all the systems demonstrate drumhead surface states spanning a large energy window showing their potential in terms of high temperature superconductivity. The slight gap induced by spin-orbit coupling (SOC) indicates that materials of the TiBe family are promising candidates for future experimental studies on nontrivial topological semimetals.