# Nodal and nodeless gap in proximity induced superconductivity: application to monolayer CuO$_2$ on BSCCO substrate

## TL;DR

This paper analyzes how proximity effects induce either nodal or nodeless superconducting gaps in monolayer CuO$_2$ on a BSCCO substrate, highlighting the role of doping levels and phase separation.

## Contribution

It provides a two-band model explaining the conditions for nodeless gaps in monolayer CuO$_2$, emphasizing the impact of doping and phase separation.

## Key findings

- Nodeless gap occurs at very high or low hole doping levels.
- Phase separation may influence the emergence of nodeless gaps.
- Proximity effects are crucial in gap behavior in monolayer CuO$_2$.

## Abstract

We present a detailed analysis on the hopping between monolayer CuO$_2$ and bulk CuO$_2$ plane in the Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ substrate. With a two-band model, we demonstrate that the nodeless gap can only exist when the hole concentration in monolayer CuO$_2$ 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.