Nontrivial Topological Properties and Synthesis of Sn ₂CoS with L2 ₁ Structure

Abstract

The band structure and surface state of Sn₂CoS with L2₁ structure are achieved by first-principles calculations. It is found that Sn₂CoS has a type-II nodal-line in the Brillouin zone and a clear drumhead-like surface state when the spin-orbit coupling is not considered. In the case of spin-orbit coupling, the nodal-line will open gap, leaving the Dirac points. Sn₂CoS has nontrivial topological properties. We try to synthesize Sn₂CoS with L2₁ structure by a direct current (DC) electrochemical deposition (ECD) method. Nanowire arrays of Sn₂CoS with L2₁ structure are successfully fabricated in an anodic aluminum oxide (AAO) template. The diameter of the typical Sn₂CoS nanowires is about 70nm, with a length about 70μm. The Sn₂CoS nanowires are single crystals with axis direction of [100] and the lattice constant determined by XRD and TEM is 6.0 Å.

Keywords: topological semimetals, Type-II Dirac point, Nanowires, Electrochemical deposition