Effect of gap anisotropy on the spin resonance peak in the superconducting state of iron-based materials

TL;DR

This paper investigates how gap anisotropy affects the spin resonance peak in iron-based superconductors, revealing that increased anisotropy shifts the peak to lower frequencies and reduces its intensity.

Contribution

It introduces a model linking gap anisotropy to the spin resonance behavior, combining a multiorbital model with spin fluctuation theory calculations.

Findings

Resonance peak shifts to higher frequencies with larger zero-amplitude gap.

Increased gap anisotropy causes the resonance peak to shift lower and diminish in intensity.

The model explains experimental observations of spin resonance in Fe-based superconductors.

Abstract

Spin resonance in the superconducting state of Fe-based materials within the multiorbital model with unequal anisotropic gaps on different Fermi surface sheets is studied. On the basis of the model gap function and the one calculated within the spin fluctuation theory of pairing, I show that the resonance peak shifts to higher frequencies with increasing the zero-amplitude gap magnitude. On the contrary, with increasing the gap anisotropy, it shifts to lower frequencies and lose some intensity.