Evidence of s-wave pairing symmetry in 2H-TaSeS*

In order to attain topological superconductivity, transition metal dichalcogenides are of great current significance. Potentially this can revolutionize the promised realization of scalable qubits. Here we report a thorough investigation into the synthesis and electromagnetic characterization of single crystals of 2H-TaSeS, which is thought to be a topological superconductor. At 4.15K, a superconducting transition is found to exist alongside a charge density wave ordering. The temperature dependence of radio frequency penetration depth using high resolution tunnel diode oscillator technique demonstrates s-wave properties in the weak coupling limit. This is in contrast to the predicted of p_x + ip_y type order parameter symmetry for topological superconductivity. Additionally, 2H-TaSeS is seen to be a typical superconductor based on the studies of critical fields. Upper critical fields exhibit moderate electronic anisotropy with a value of 1.52. DFT simulations further support the likelihood of superconducting behavior in TaSeS and indicate that the P6₃mc space group has the most stable structure. Phonon dispersion curves with negative values confirm the possibility of existence of CDW in 2H- TaSeS. Overall, all studies on single crystals of TaSeS shows conventional type-II superconductivity without any indication of topological characteristics.