Lattice and electronic anomalies of CaFe2As2 studied by Raman spectroscopy

TitleLattice and electronic anomalies of CaFe2As2 studied by Raman spectroscopy
Publication TypeJournal Article
Year of Publication2008
AuthorsChoi KY, Wulferding D, Lemmens P, Ni N, Bud'ko SL, Canfield PC
Journal TitlePhysical Review B
Date Published12
ISBN Number1098-0121
Accession NumberISI:000262244400017
Keywordscalcium compounds, electronic density of states, iron compounds, light scattering, phonons, raman spectra, solid-state phase transformations, spectral line breadth, superconductivity

We report inelastic light-scattering experiments on CaFe2As2 in the temperature range of 4-290 K. In in-plane polarizations two Raman-active phonon modes are observed at 189 and 211 cm(-1), displaying A(1g) and B-1g symmetries, respectively. Upon heating through the tetragonal-to-orthorhombic transition at about T-S=173 K, the B-1g phonon undergoes a discontinuous drop of frequency by 4 cm(-1), whereas the A(1g) phonon shows a suppression of the integrated intensity. Their linewidth increases strongly with increasing temperature and saturates above T-S. This suggests (i) a first-order structural phase transition and (ii) a drastic change in charge distribution within the FeAs plane through T-S.

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