Role of Interactions in the Energy of the Spin Resonance Peak in Fe-Based Superconductors

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, 2ΔL. In the second case, the energy scale corresponds to the sum of smaller and larger gap magnitudes, ΔL +ΔS. Increasing the values of the Hubbard interaction and the Hund’s exchange, we observe a shift of the spin resonance energy to lower frequencies.