Recently, 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. In this work, 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. At 77 K, we observed the spatial variation of the local tunneling conductance (dI/dV) of the 2M-WS2 thin flakes by scanning tunneling spectroscopy (STS). 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.

中文翻译：

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用于超导的二维2M-WS ₂纳米层

最近，一种新发现的VIB基族过渡金属二硫化碳（TMD）材料2M-WS ₂由于其有趣的物理特性（如拓扑超导性，无节点超导性和各向异性的Majorana键合态）而引起了广泛关注。但是，生长高质量2M-WS ₂块状晶体的技术及其在纳米尺度上的物理性质的研究仍然受到限制。在这项工作中，我们报告了一种生长高质量2M-WS ₂单晶的新途径，并观察了其薄层中的超导性。生长的2M-WS ₂的晶体结构通过X射线衍射（XRD）和扫描隧道显微镜（STM）确定晶体。2M-WS ₂晶体的化学组成通过能量色散X射线光谱（EDS）分析确定。在77 K下，我们通过扫描隧道光谱（STS）观察了2M-WS2薄片的局部隧道电导（d I / d V）的空间变化。我们的低温传输测量结果显示了25 nm厚的2M-WS ₂薄片的超导性的清晰特征，其临界温度（T _C）为约8.5 K，在T处的上限临界电场为约2.5 T = 1.5K。我们的工作可能会为研究简单2D TMD材料在原子尺度上的拓扑超导性提供新的机会。