Anomalous phonons in CaFe 2 As 2 explored by inelastic neutron scattering3

Mittal, R.; Chaplot, S. L.; Brückel, Thomas; Thamizhavel, A.; Kumar, N.; Pintschovius, L.; Dhar, S. K.; Reznik, D.; Bohnen, K-P; Heid, R.; Su, Y.; Lamago, D.

doi:10.1088/1742-6596/251/1/012008

Journal Article

FZJ-2017-06677

Anomalous phonons in CaFe 2 As 2 explored by inelastic neutron scattering3

Mittal, R. (Corresponding author) ; Pintschovius, L. ; Lamago, D. ; Heid, R. ; Bohnen, K.-P. ; Reznik, D. ; Chaplot, S. L. ; Su, Y.FZJ* ; Kumar, N. ; Dhar, S. K. ; Thamizhavel, A. ; Brückel, T.FZJ*

2010
IOP Publ. Bristol

Journal of physics / Conference Series 251, 012008 - (2010) [10.1088/1742-6596/251/1/012008]

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Please use a persistent id in citations: http://hdl.handle.net/2128/15321 doi:10.1088/1742-6596/251/1/012008

Abstract: Extensive inelastic neutron scattering measurements of phonons on a single crystal of CaFe2As2 allowed us to establish a fairly complete picture of phonon dispersions in the main symmetry directions. The phonon spectra were also calculated by density functional theory (DFT) in the local density approximation (LDA). There are serious discrepancies between calculations done for the optimized structure and experiment, because the optimised structure is not the ambient pressure structure but is very close to the "collapsed" structure reached at p = 3.5 kbar. However, if the experimental crystal structure is used the calculation gives correct frequencies of most phonons. The most important new result is that linewidths/frequencies of certain modes are larger/softer than predicted by DFT-LDA. We also observed strong temperature dependence of some phonons near the structural phase transition near 172 K. This behavior may indicate anomalously strong electron phonon coupling and/or anharmonicity, which may be important to the mechanism of superconductivity.

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