Raman spectroscopy of RFeAsO (R =Sm, La)

Abstract

We report the polarized Raman spectra of undoped RFeAsO (R =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), and 345 cm-1 (B1g, O) for SmFeAsO; and 162 cm-1 (A1g, La), 208 cm-1 (A1g, As), 201 cm-1 (B1g, Fe), and 316 cm-1 (B1g, O) for LaFeAsO. © 2008 The American Physical Society.