Lattice Dynamics of LaFeAsO_{1-x}F_{x} and PrFeAsO_{1-y} via Inelastic X-Ray Scattering and First-Principles Calculation

TL;DR

This study combines inelastic X-ray scattering and first-principles calculations to analyze the lattice dynamics of iron-based superconductors LaFeAsO and PrFeAsO, revealing phonon behavior and bond softening effects.

Contribution

It introduces a combined experimental and computational approach to understand lattice vibrations in LaFeAsO_{1-x}F_{x} and PrFeAsO_{1-y}, highlighting bond softening as a key factor.

Findings

Phonon density of states approximated from powder samples.

Dispersion relations measured from a single crystal.

A model with 30% softened Fe-As bond matches experimental data.

Abstract

The lattice dynamics of LaFeAsO_{1-x}F_{x} (x=0, 0.1) and PrFeAsO_{1-y} (y~0.1) are investigated using inelastic x-ray scattering and ab-initio calculation. Measurements of powder samples provide an approximation to the phonon DOS, while dispersion is measured from a single crystal of PrFeAsO_{1-y}. A model that agrees reasonably well with all of the data at room temperature is built from results of ab-initio calculations by softening the strength of the Fe-As bond by 30%.