Emergence of superconductivity in 2D Cu 0.65 NbS 2 nanosheets via copper ion hopping

Layered materials with intercalated ions exhibit a variety of intriguing physical and chemical properties. To obtain the exotic two-dimensional (2D) materials, doping and alteration of crystals by ionic guest species are widely used in materials science. However, in ion-intercalated layered materials, the properties induced by the change of interlayered structures are rarely studied. Hence, we demonstrate the emergence of superconductivity by a new interlayered structure in Cu 0.65 NbS 2 nanosheets. The interlayered Cu occupancy changes from ordered tetrahedral sites in bulk to mixed tetrahedral sites as the thickness reduces, which turns the normal-metal crystal into a superconductor. Prominently, the superconducting transition temperature shows a strong thickness dependence with a dome-like shape, which is different with the NbS 2 system. The arrangement of the interlayered ions can be a new method for promoting the investigation of novel intrinsic phenomenon in the 2D realm.