We propose and characterize a new Z2 class of topological semimetals with a vanishing spin--orbit interaction. The proposed topological semimetals are characterized by the presence of bulk one-dimensional (1D) Dirac Line Nodes (DLNs) and two-dimensional (2D) nearly-flat surface states, protected by inversion and time--reversal symmetries. We develop the Z2 invariants dictating the presence of DLNs based on parity eigenvalues at the parity--invariant points in reciprocal space. Moreover, using first-principles calculations, we predict DLNs to occur in Cu3N near the Fermi energy by doping non-magnetic transition metal atoms, such as Zn and Pd, with the 2D surface states emerging in the projected interior of the DLNs. This paper includes a brief discussion of the effects of spin--orbit interactions and symmetry-breaking as well as comments on experimental implications.
@article{arxiv.1504.03807,
title = {Dirac Line Nodes in Inversion Symmetric Crystals},
author = {Youngkuk Kim and Benjamin J. Wieder and C. L. Kane and Andrew M. Rappe},
journal= {arXiv preprint arXiv:1504.03807},
year = {2015}
}