Nodal and nodeless gap in proximity induced superconductivity: application to monolayer CuO2 on BSCCO substrate

Abstract

We present a detailed analysis on the hopping between monolayer CuO2 and bulk CuO2 plane in the Bi2Sr2CaCu2O8+δ substrate. With a two-band model, we demonstrate that the nodeless gap can only exist when the hole concentration in monolayer CuO2 plane is very large or very small. We argued that the possible phase separation may play important role in the recent experimental observation of nodeless gap.