Superconductivity in Ca-intercalated bilayer silicene

Within first-principles calculations, we explore superconductivity in Ca-intercalated bilayer silicene compound, Si2CaSi2. This arises from the coupling of interlayer flower-like Γ-centered Fermi surface formed by the hybridization of Ca-3d and Si-3pz orbitals with low-energy out-of-plane vibrations enabled by silicene’s buckling. The consequent large electron-phonon coupling, as evident from the Eliashberg spectral function leads to superconductivity below 5.4 K in this two-dimensional covalent system. Our results reveal the key control parameters to achieve superconductivity in experimentally synthesizable silicon-based thin materials that can find diverse applications.