Superconductivity and Charge Density Wave in SnSe₂-based Heterostructures

We report the direct observation of interface superconductivity and interface-induced charge density wave on monolayer SnSe₂-based heterostructures. Tunneling spectrums on epitaxial monolayer SnSe₂ grown on graphited SiC(0001) substrate showed a fully-gapped superconducting state with rather conventional character. Occurrence of vortices under external magnetic field further confirmed the superconductivity. We attribute the superconductivity to the two-dimensional gas formed at the interface of SnSe₂ and graphene. Besides, charge density waves (CDW) with 2 × 2 periodicity were observed in SnSe₂ thin films grown on SrTiO₃(001) and Si(111), which disappear as the film thickness increases. Our finding opens new perspectives to understand not only interface superconductivity but also possible relationship between supercondcuvity and CDW.