Topological properties of CsCl type superconducting materials

Abstract

By using the first-principles electronic structure calculation, we have studied electronic band structures and topological properties of CsCl type binary superconductors RuTi and OsTi. Due to the protection of higher crystal symmetry, there are three-dimensional nodal rings around high symmetry points X, Y and Z without spin-orbital coupling (SOC). When SOC is considered, we find the topological phase transition from strong topological insulator phase in RuTi to Dirac semimetal in OsTi. The corresponding surface states are consistent with these nontrivial topologies. We also find strong topological insulator phases near Fermi level in isostructure material MgRh. Based on the topological surface states, the interface of heterostructure of superconductor RuTi (OsTi) and doped topological material MgRh could realize observable topological superconductivity. The nontrivial topological properties in binary superconductors RuTi and OsTi provide us new desirable avenues to study Majorana bound states in vortex cores of topological superconductor.