# Effective pairing interaction in a system with an incipient band

## TL;DR

This paper demonstrates that superconductivity in highly electron-doped FeSe systems can be explained by an effective retarded attractive interaction between electrons near the Fermi surface, using quantum Monte Carlo simulations.

## Contribution

It introduces a dynamic cluster quantum Monte Carlo approach to model pairing mechanisms involving incipient bands in superconductors.

## Key findings

- Superconductivity can be explained by an effective retarded attraction.
- Quantum Monte Carlo simulations support the pairing mechanism.
- Incipient bands influence the pairing interaction.

## Abstract

The nature and mechanism of superconductivity in the extremely electron-doped FeSe based superconductors continues to be a matter of debate. In these systems, the hole-like band has moved below the Fermi energy, and various spin-fluctuation theories involving pairing between states near the electron Fermi surface and states of this incipient band have been proposed. Here, using a dynamic cluster quantum Monte Carlo calculation for a bilayer Hubbard model we show that the pairing in these systems can be understood in terms of an effective retarded attractive interaction between electrons near the electron Fermi surface.