Ab initio study of the PbTaSe2-related superconducting topological metals

Recent reports have demonstrated the Z(2) topological property of the superconductor PbTaSe2 (Tc similar to 3.8 K). PbTaSe2 simultaneously exhibits superconductivity and nontrivial Z(2) topology without the need for doping or proximity effect. Scanning tunneling microscopy confirms that the topological surface states are gapped by superconductivity, indicating the likelihood of the chiral p(x) + ip(y) pairing mechanism. Motivated by these exciting findings, we predict by means of the first-principles scheme that ABSe(2) (A = Pb or Sn and B = Ta or Nb) is also a superconductor with nontrivial Z(2) topology. Among these, SnNbSe2 shows the highest T-c similar to 7.0 K. Due to the fact that the required energy resolution to detect the Majorana bound states is of the order of Delta(2)/epsilon(F), the predicted higher T-c of ABSe(2) may help mitigate some experimental challenges and provides a better platform for the exploration of the topological superconductivity.