Transition Metal Dichalcognides (TMDs) continue to attract scientific interest due to their intriguing physical properties and potential technological applications. Here, we report the emergence of a pressure-induced dome-shaped superconductivity in PdSe₂ with a maximum critical temperature (T_c) of 13.1 K at 23 GPa, which is so far the highest T_c among TMDs family.
Lattice dynamics studies under pressure revealed a strong correlation between Se-Se dumbbells bonding and T_c. In addition, Ab initio calculations of the PdSe₂ electronic structure show the existence of topological non-trivial state with Dirac crossing and nodal lines in the vicinity of Fermi level.
PdSe₂ provides therefore an exciting example to study the relationship between superconductivity and topologically non-trivial states, which can lead to discovery of novel superconducting states. We have revisited other TMD compounds to search for new superconductors. The related compounds NiSe₂ and PdS₂ have also been studied in comparison with PdSe₂. These compounds are not only interesting from the fundamental research prespective, but also for technological application as the electronically-driven insulator-metal transition at relatively low pressures could be promising in electronics applications such as memory devices.