This title appears in the Scientific Report :
2010
Please use the identifier:
http://dx.doi.org/10.1103/PhysRevB.81.144502 in citations.
Please use the identifier: http://hdl.handle.net/2128/10991 in citations.
Pressure dependence of phonon modes across the tetragonal to collapsed tetragonal phase transition in CaFe2As2
Pressure dependence of phonon modes across the tetragonal to collapsed tetragonal phase transition in CaFe2As2
The pressure dependence of a large number of phonon modes in CaFe2As2 with energies covering the full range of the phonon spectrum has been studied using inelastic x-ray and neutron scatterings. The pressure range was large enough to cover the first-order phase transition into the so-called collapse...
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Personal Name(s): | Mittal, R. |
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Heid, R. / Bosak, A. / Forrest, T.R. / Chaplot, S.L. / Lamago, D. / Reznik, D. / Bohnen, K.P. / Su, Y. / Kumar, C. M. N. / Dhar, S.K. / Thamizhavel, A. / Rueegg, Ch. / Krisch, M. / McMorrow, D.F. / Brückel, T. / Pintschovius, L. | |
Contributing Institute: |
JARA-FIT; JARA-FIT JCNS; JCNS Neutronenstreuung; IFF-5 Streumethoden; IFF-4 |
Published in: | Physical Review B Physical review / B, 81 81 (2010 2010) 14 14, S. 144502 144502 |
Imprint: |
College Park, Md.
APS
2010
|
Physical Description: |
144502 |
DOI: |
10.1103/PhysRevB.81.144502 |
Document Type: |
Journal Article |
Research Program: |
Großgeräte für die Forschung mit Photonen, Neutronen und Ionen (PNI) BioSoft: Makromolekulare Systeme und biologische Informationsverarbeitung |
Series Title: |
Physical Review B
81 |
Subject (ZB): | |
Link: |
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Publikationsportal JuSER |
Please use the identifier: http://hdl.handle.net/2128/10991 in citations.
The pressure dependence of a large number of phonon modes in CaFe2As2 with energies covering the full range of the phonon spectrum has been studied using inelastic x-ray and neutron scatterings. The pressure range was large enough to cover the first-order phase transition into the so-called collapsed phase where the c-axis contracts by about 6% whereas a and b axes expand by about 1.5%. Our main result is that pressure-induced phonon frequency shifts are well explained by the changes in relevant bond lengths throughout the pressure range, including those associated with the first-order phase transition. Specifically, the frequencies of phonons polarized in the ab plane as well as the Fe-As bond lengths change little across the phase transition. On the other hand, the transverse-acoustic phonons propagating along the c direction stiffen very significantly in response to the large contraction of the bonds along the c axis. Nonmagnetic density-functional calculations describe the frequencies in both the zero pressure and in the collapsed phase in a satisfactory way if based on the respective experimental crystal structures. This suggests that there is no need to invoke changes in magnetic moments on Fe atoms to explain the pressure-induced frequency shifts. |