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arXiv · 0910.1565

Phonon anomaly in BaFe2As2

A. Akrap·J. J. Tu·L. J. Li·G. H. Cao·X. A. Xu·C. C. Homes
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Abstract

The detailed optical properties of BaFe2As2 have been determined over a wide frequency range above and below the structural and magnetic transition at T_N = 138 K. A prominent in-plane infrared-active mode is observed at 253 cm^{-1} (31.4 meV) at 295 K. The frequency of this vibration shifts discontinuously at T_N; for T < T_N the frequency of this mode displays almost no temperature dependence, yet it nearly doubles in intensity. This anomalous behavior appears to be a consequence of orbital ordering in the Fe-As layers.

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A. Akrap, J. J. Tu, L. J. Li, G. H. Cao, X. A. Xu, C. C. Homes. 2009-10-08. Phonon anomaly in BaFe2As2. https://doi.org/10.1103/physrevb.80.180502

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