Prediction of superconductivity in a series of tetragonal transition metal dichalcogenides

Transition metal dichalcogenides (TMDCs) represent a well-known material family with diverse structural phases and rich electronic properties; they are thus an ideal platform for studying the emergence and exotic phenomenon of superconductivity (SC). Herein, we propose the existence of tetragonal TMDCs with a distorted Lieb (dLieb) lattice structure and the stabilized transition metal disulfides (MS₂), including dLieb-ZrS₂, dLieb-NbS₂, dLieb-MnS₂, dLieb-FeS₂, dLieb-ReS₂, and dLieb-OsS₂. Except for semiconducting dLieb-ZrS₂ and magnetic dLieb-MnS₂, the rest of metallic dLieb-MS₂ was found to exhibit intrinsic SC with the transition temperature (T_C) ranging from ∼5.4 to ∼13.0 K. The T_C of dLieb-ReS₂ and dLieb-OsS₂ exceeded 10 K and was higher than that of the intrinsic SC in the known metallic TMDCs, which is attributed to the significant phonon-softening enhanced electron-phonon coupling strength. Different from the Ising spin-orbit coupling (SOC) effect in existing non-centrosymmetric TMDCs, the non-magnetic dLieb-MS₂ monolayers exhibit the Dresselhaus SOC effect, which is featured by in-plane spin orientations and will give rise to the topological SC under proper conditions. In addition to enriching the structural phases of TMDCs, our work predicts a series of SC candidates with high intrinsic T_C and topological non-triviality used for fault-tolerant quantum computation.