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arXiv · 1111.6707

Temperature-dependent Raman study of CeFeAsO0.9F0.1 Superconductor: Crystal field excitations, phonons and their coupling

Pradeep Kumar·Anil Kumar·Surajit Saha·D. V. S. Muthu·J. Prakash·U. V. Waghmare·A. K. Ganguli·A. K. Sood
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Abstract

We report temperature-dependent Raman spectra of CeFeAsO0.9F0.1 from 4 K to 300 K in spectral range of 60 to 1800 cm-1 and interpret them using estimates of phonon frequencies obtained from first-principles density functional calculations. We find evidence for a strong coupling between the phonons and crystal field excitations; in particular Ce3+ crystal field excitation at 432 cm-1 couples strongly with Eg oxygen vibration at 389 cm-1 . Below the superconducting transition temperature, the phonon mode near 280 cm-1 shows softening, signaling its coupling with the superconducting gap. The ratio of the superconducting gap to Tc thus estimated to be ~ 10 suggests CeFeAsO0.9F0.1 as a strong coupling superconductor. In addition, two high frequency modes observed at 1342 cm-1 and 1600 cm-1

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Pradeep Kumar, Anil Kumar, Surajit Saha, D. V. S. Muthu, J. Prakash, U. V. Waghmare, A. K. Ganguli, A. K. Sood. 2011-11-29. Temperature-dependent Raman study of CeFeAsO0.9F0.1 Superconductor: Crystal field excitations, phonons and their coupling. https://doi.org/10.1088/0953-8984%2F22%2F25%2F255402

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