Interference-induced surface superconductivity: Enhancement by tuning the Debye energy

In the usual perception, surface superconductivity is associated with the surface nucleation of a superconducting condensate above the upper critical field in type-II superconductors or with a rearrangement of phonon properties and the electron-phonon coupling near surfaces/interfaces. Recently, it has been found that there is another example when the surface superconducting temperature is increased up to $20--25%$ as compared to the bulk one due to constructive interference of superconducting pair states. In the present work, we demonstrate that in fact, such an interference-induced enhancement can be much more pronounced, up to nearly $70%$. Furthermore, here it is shown that such an interference enhancement persists over a wide range of microscopic parameters.