# Role of interactions in the energy of the spin resonance peak in Fe-based superconductors

## TL;DR

This paper investigates how interactions influence the energy of the spin resonance peak in iron-based superconductors, considering different gap scenarios and interaction strengths within a five-orbital model.

## Contribution

It provides a detailed analysis of the spin response in iron-based superconductors, highlighting the effects of interactions and gap structures on the resonance energy.

## Key findings

- Resonance peak appears below 2Δ_L in equal-gap case.
- Resonance energy shifts to lower frequencies with increased interactions.
- Different gap configurations determine the characteristic energy scale.

## Abstract

We consider the spin response within the five-orbital model for iron-based superconductors and study two cases: equal and unequal gaps in different bands. In the first case, the spin resonance peak in the superconducting state appears below the characteristic energy scale determined by the gap magnitude, $2\Delta_L$. In the second case, the energy scale corresponds to the sum of smaller and larger gap magnitudes, $\Delta_L + \Delta_S$. Increasing the values of the Hubbard interaction and the Hund's exchange, we observe a shift of the spin resonance energy to lower frequencies.