# Possible spin excitation structure in monolayer FeSe grown on SrTiO$_{3}$

## TL;DR

This paper models the electronic structure and spin excitations in monolayer FeSe on SrTiO3, suggesting a unique pairing symmetry and spin resonance behavior distinct from other FeSe superconductors.

## Contribution

It introduces a tailored tight-binding and pairing model for monolayer FeSe on SrTiO3, analyzing its spin excitation spectrum and sign-changing order parameter.

## Key findings

- Resonance-like spin excitation depends on sign change of SC gap.
- Resonance occurs at different momentum space locations compared to other FeSe superconductors.
- Fermi surface shape and pairing symmetry are distinct in monolayer FeSe on SrTiO3.

## Abstract

Based on recent high-resolution angle-resolved photoemission spectroscopy measurement in monolayer FeSe grown on SrTiO$_{3}$, we constructed a tight-binding model and proposed a superconducting (SC) pairing function which can well fit the observed band structure and SC gap anisotropy. Then we investigated the spin excitation spectra in order to determine the possible sign structure of the SC order parameter. We found that a resonance-like spin excitation may occur if the SC order parameter changes sign along the Fermi surfaces. However, this resonance is located at different locations in momentum space compared to other FeSe-based superconductors, suggesting that the Fermi surface shape and pairing symmetry in monolayer FeSe grown on SrTiO$_{3}$ may be different from other FeSe-based superconductors.