nanolayers for superconductivity

A newly discovered VIB group transition metal dichalcogenide (TMD) material 2M-WS₂ has attracted extensive attention due to its interesting physical properties such as topological superconductivity, nodeless superconductivity, and anisotropic Majorana bound states. However, the techniques to grow high-quality 2M-WS₂ bulk crystals and the study of their physical properties at the nanometer scale are still limited. Here, we report a new route to grow high-quality 2M-WS₂ single crystals and the observation of superconductivity in its thin layers. The crystal structure of the as-grown 2M-WS₂ crystals was determined by X-ray diffraction (XRD) and scanning tunneling microscopy (STM). The chemical composition of the 2M-WS₂ crystals was determined by energy dispersive x-ray spectroscopy (EDS) analysis. Our low temperature transport measurements demonstrate clear signatures of superconductivity of a 25 nm-thick 2M-WS₂ flake with a critical temperature (T_C) of ~8.5 K and an upper critical field of ~ 2.5 T at T = 1.5 K. Our work may pave new opportunities in studying the topological superconductivity at the atomic scale in simple 2D TMD materials.