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arXiv · 1405.1407

Superconductivity-induced Phonon Renormalization on NaFe$_{1-x}$Co$_{x}$As

Y. J. Um·Yunkyu Bang·B. H. Min·Y. S. Kwon·M. Le Tacon
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Abstract

We report a study of the lattice dynamics in superconducting NaFeAs (Tc = 8 K) and doped NaFe0.97Co0.03As (Tc = 20 K) using Raman light scattering. Five of the six phonon modes expected from group theory are observed. In contrast with results obtained on iso-structural and iso-electronic LiFeAs, anomalous broadening of Eg(As) and A1g(Na) modes upon cooling is observed in both samples. In addition, in the Co-doped sample, a superconductivity-induced renormalization of the frequency and linewidth of the B1g(Fe) vibration is observed. This renormalization can not be understood within a single band and simple multi-band approaches. A theoretical model that includes the effects of SDW correlations along with sign-changing s-wave pairing state and interband scattering has been developed to explain the observed behavior of the B1g(Fe) mode.

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Y. J. Um, Yunkyu Bang, B. H. Min, Y. S. Kwon, M. Le Tacon. 2014-05-06. Superconductivity-induced Phonon Renormalization on NaFe$_{1-x}$Co$_{x}$As. https://doi.org/10.1103/physrevb.89.184510

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