Temperature dependence and resonance effects in Raman scattering of phonons in NdFeAsO${}_x$F${}_{1-x}$ single crystals

Abstract

We report plane-polarized Raman scattering spectra of iron oxypnictide superconductor NdFeAsO${}_{1-x}$F${}_x$ single crystals with varying fluorine $x$ content. The spectra exhibit sharp and symmetrical phonon lines with a weak dependence on fluorine doping $x$. The temperature dependence does not show any phonon anomaly at the superconducting transition. The Fe related phonon intensity shows a strong resonant enhancement below 2 eV. We associate the resonant enhancement to the presence of an interband transition around 2 eV observed in optical conductivity. Our results point to a rather weak coupling between Raman-active phonons and electronic excitations in iron oxypnictides superconductors.

4 pages, 3 figures, to appear in Phys. Rev. B

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Cited by in corpus (2)

• Anharmonic softening of Raman active phonons in Iron-Pnictides; estimating the Fe isotope effect due to anharmonic expansion
• Temperature dependent local structure of NdFeAsO1-xFx system using arsenic K-edge extended x-ray absorption fine structure