Order parameter symmetry in superconducting 2H-TaSeS.

Superconductors based on transition metal dichalcogenides are of substantial current relevance towards the material realization of topological superconductivity. Here, we report a detailed study on the synthesis and characterization of single crystals of 2H-TaSeS. A superconducting transition is confirmed at4.15Kthat coexists with a charge-density wave ordering at66K. The temperature dependence of the RF penetration depth indicates s-wave characteristics in the weak-coupling limit. Moderate electronic anisotropy is observed in the upper critical fields. DFT calculations confirm that the most stable structure belongs to theP63mcspace group. Negative values in the phonon dispersion curves verify the possibility of coexisting superconductivity with a charge-density wave in 2H-TaSeS. We also study vortex dynamics in this novel superconductor. Overall, our analysis suggests that 2H-TaSeS is a conventional Type-II superconductor without any evidence for topological superconductivity.