Octastanene Halogenide: A Family of Two-dimensional Nodal Line Semimetals and Topological Insulators

Abstract

With the first principle calculation and k-p model, we find that the Octastanene halogenide is a node line semimetal(NLs) without spin-orbit coupling(soc), forming a fermi ring centered on point G and protected by mirror symmetry. The band simulated by the k-p model fits well with the band calculated by GGA-PBE at point G, and the energy dispersion calculated by the Hamiltonian of the model explains well the formation of node rings. Under the SOC effect, NLs become a two dimensional Topological Insulators(TIs). With the increase of atomic number, the large band gap reaches about 0.16 ev, and the clear spiral edge state of the quantum spin hall effect is obtained. The phonon spectra of the two structures show that they are dynamically stable. These findings provide a new two dimensional material series for the future design and manufacture of NLs and TIs.