Thickness-dependent superconductivity in layered 2M-WS₂

Topological superconductivity has become an active research field in recent years because it not only opens up opportunities in quantum physics, but also paves a way to revolutionize the current computing technology. Since the discovery of superconductivity in a binary transition metal dichalcogenide (TMD), 2M-WS₂, in 2019, study of the possible topological properties and the corresponding pairing symmetry has attracted extensive attention. Here, we will first introduce the preparation of high quality 2M-WS₂ nanolayers and then discuss the thickness dependence of the superconductivity in 2M-WS₂. We find that the superconductivity in 2M-WS₂ can persistent down to few layers. The corresponding transition temperature decreases from ~ 8.7 K to 6.9 K as the thickness varies from 40 nm to 3 nm. In the end, the pairing symmetry will also be discussed. Our discovery may provide evidence of the existence of topological properties in 2M-WS₂ at the atomic scale.