The magnetic excitation spectra in BaFe$_{2}$As$_{2}$: a two-particle approach within DFT+DMFT

TL;DR

This study uses a combined DFT+DMFT approach to accurately model magnetic excitation spectra in BaFe₂As₂, aligning well with experimental INS data without requiring nematic order.

Contribution

It introduces a two-particle response function calculation within DFT+DMFT that reproduces experimental magnetic spectra without symmetry breaking.

Findings

Reproduces all features observed in inelastic neutron scattering.

Explains magnetic excitations through one-particle and collective modes.

Does not require nematic order to match experimental data.

Abstract

We study the magnetic excitation spectra in the paramagnetic state of BaFe$_{2}$As$_{2}$ from the \textit{ab initio} perspective. The one-particle excitation spectrum is determined within the combination of the density functional theory and the dynamical mean-field theory method. The two-particle response function is extracted from the local two-particle vertex function, also computed by the dynamical mean field theory, and the polarization function. This method reproduces all the experimentally observed features in inelastic neutron scattering (INS), and relates them to both the one particle excitations and the collective modes. The magnetic excitation dispersion is well accounted for by our theoretical calculation in the paramagnetic state without any broken symmetry, hence nematic order is not needed to explain the INS experimental data.