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

TitleInfluence of magnetism on phonons in CaFe2As2 as seen via inelastic x-ray scattering
Publication TypeJournal Article
Year of Publication2009
AuthorsHahn SE, Lee Y, Ni N, Canfield PC, Goldman AI, McQueeney RJ, Harmon BN, Alatas A, Leu BM, Alp EE, Chung DY, Todorov IS, Kanatzidis MG
Journal TitlePhysical Review B
Date Published06/01
ISBN Number1098-0121
Accession NumberISI:000267699300019
Keywordsab initio calculations, antiferromagnetic materials, arsenic alloys, calcium alloys, electron spin polarisation, iron alloys, iron-pnictides, magnetic moments, phonon dispersion relations, x-ray scattering

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.

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