U-shape and V-shape gaps near interface of quasi-two-dimensional superconductor and normal metal

Proximity effect between superconductor and normal metal on finite quasi-2D lattices is investigated by using Bogoliubov–de Gennes equation. By introducing two types of spatial distribution of attractive interaction near the interface, the step like distribution and the exponential decay distribution, we explain the U-shape and V-shape gaps observed in STM experiments.