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Phys. Rev. B 79, 220511(R) (2009) [4 pages]

Influence of magnetism on phonons in CaFe2As2 as seen via inelastic x-ray scattering

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S. E. Hahn*, Y. Lee, N. Ni, P. C. Canfield, A. I. Goldman, R. J. McQueeney†, and B. N. Harmon
Department of Physics and Astronomy and Ames Laboratory, Iowa State University, Ames, Iowa 50010, USA

A. Alatas, B. M. Leu, and E. E. Alp
Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA

D. Y. Chung and I. S. Todorov
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA

M. G. Kanatzidis
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA and Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA

Received 27 February 2009; revised 14 May 2009; published 19 June 2009

In the iron pnictides, the strong sensitivity of the iron magnetic moment to the arsenic position suggests a significant relationship between phonons and magnetism. We measured the phonon dispersion of several branches in the high-temperature tetragonal phase of CaFe2As2 using inelastic x-ray scattering on single-crystal samples. These measurements were compared to ab initio calculations of the phonons. Spin-polarized calculations imposing the antiferromagnetic order present in the low-temperature orthorhombic phase dramatically improve agreement between theory and experiment. This is discussed in terms of the strong antiferromagnetic correlations that are known to persist in the tetragonal phase.

© 2009 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.79.220511
DOI:
10.1103/PhysRevB.79.220511
PACS:
74.25.Kc, 74.25.Ha, 78.70.Ck, 63.20.−e

*shahn@ameslab.gov

†mcqueeney@ameslab.gov

 
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