Collective magnetic excitations of $C_{4}$ symmetric magnetic states in iron-based superconductors

TL;DR

This paper investigates the collective magnetic excitations in $C_{4}$ symmetric spin-density wave states of iron-based superconductors, highlighting their orbital character and how damping effects influence their spectra.

Contribution

It introduces an itinerant multiorbital approach to analyze magnetic excitations, revealing orbital polarization unique to $C_{4}$ symmetric states and aiding in identifying magnetic phases.

Findings

Orbital polarization is inherent to magnetic excitations in $C_{4}$ states.

Damping effects from particle-hole continuum significantly modify excitation spectra.

Distinct orbital features can help identify different magnetic states in iron-based superconductors.

Abstract

We study the collective magnetic excitations of the recently discovered $C_{4}$ symmetric spin-density wave states of iron-based superconductors with particular emphasis on their orbital character based on an itinerant multiorbital approach. This is important since the $C_{4}$ symmetric spin-density wave states exist only at moderate interaction strengths where damping effects from a coupling to the continuum of particle-hole excitations strongly modifies the shape of the excitation spectra compared to predictions based on a local moment picture. We uncover a distinct orbital polarization inherent to magnetic excitations in $C_{4}$ symmetric states, which provide a route to identify the different commensurate magnetic states appearing in the continuously updated phase diagram of the iron-pnictide family.