The optical phonon spectrum of SmFeAsO

TL;DR

This study combines experimental Raman and Infrared spectroscopy with ab-initio calculations to analyze the phonon spectrum of SmFeAsO, providing insights into its lattice dynamics and potential role in superconductivity.

Contribution

It offers a comprehensive comparison of experimental and theoretical phonon spectra in SmFeAsO and LaFeAsO, highlighting the predictive power of ab-initio methods and suggesting phonons' role in superconductivity.

Findings

Measured phonon frequencies match theoretical predictions

High-frequency phonons may influence superconducting pairing

Ab-initio methods effectively describe lattice dynamics

Abstract

We measured the Raman and the Infrared phonon spectrum of SmFeAsO polycrystalline samples. We also performed Density Functional Theory calculations within the pseudopotential approximation to obtain the structural and dynamical lattice properties of both the SmFeAsO and the prototype LaFeAsO compounds. The measured Raman and Infrared phonon frequencies are well predicted by the optical phonon frequencies computed at the Gamma point, showing the capability of the employed ab-initio methods to describe the dynamical properties of these materials. A comparison among the phonon frequencies of different oxypnictides suggests a possible role of the high frequency phonons in the pairing mechanism leading to superconductivity in these materials.