Raman phonons in ReOFeAs (Re= Sm, La)

TL;DR

This study presents polarized Raman spectra of undoped ReOFeAs (Re=Sm, La), identifying specific phonon modes and their symmetries related to atomic vibrations at room temperature.

Contribution

The paper provides detailed Raman phonon frequencies and symmetries for SmOFeAs and LaOFeAs, expanding understanding of lattice vibrations in these materials.

Findings

Identified four Raman phonons with specific frequencies and symmetries for SmOFeAs.

Identified four Raman phonons with specific frequencies and symmetries for LaOFeAs.

Spectra show sharp phonon lines with weak electronic background.

Abstract

We report the polarized Raman spectra of undoped ReOFeAs (Re = Sm, La) collected at room temperature from $ab$ surfaces of impurity free microcrystals. The spectra exhibit sharp phonon lines on very weak electronic scattering background. The frequency and symmetry of the four Raman phonons involving out-of-plane atomic vibrations are found at 170 cm-1 (A1g, Sm), 201 cm-1 (A1g, As), 208 cm-1 (B1g, Fe), 345 cm-1(B1g, O) for SmOFeAs, and 162 cm-1 (A1g, La), 208 cm-1 (A1g, As), 201 cm-1 (B1g, Fe), 316 cm-1 (B1g, O) for LaOFeAs.