Interfacial effects on the superconducting properties of LaSi2(112) films on Si(111)

Abstract

Superconducting films are fascinating due to their tunability associated with the interfacial effects. Here we report the superconductivity of single-crystalline $\mathrm{LaS}{\mathrm{i}}_{2}(112)$ films epitaxially grown on Si(111) substrates, which exhibit the superconducting transition temperature $({T}_{c})$ of 3.2 K in films thicker than 21 monolayers (ML) in the strong-coupling regime. At the interface, the $\mathrm{LaS}{\mathrm{i}}_{2}$ films bear the tensile strain, leading to the formation of thickness-dependent stripes. The local superconducting gap varies in real space in accordance with the stripes. In some areas with the thickness of 10--21 ML the superconductivity is enhanced, while in films thinner than 10 ML the superconductivity is suppressed due to the suppression of electronic states at the Fermi level. Our work provides insights into the interfacial effects on the superconductivity of epitaxial compound films from both lattice and electronic aspects.