Vibrational anomalies in AFe2As2 (A=Ca, Sr, and Ba) single crystals

dc.contributor.author Homes, C. C.
dc.contributor.author Dai, Y. M.
dc.contributor.author Akrap, Ana
dc.contributor.author Canfield, Paul
dc.contributor.author Bud’ko, Sergey
dc.contributor.author Canfield, Paul
dc.contributor.department Ames National Laboratory
dc.contributor.department Physics and Astronomy
dc.date 2019-09-20T14:53:40.000
dc.date.accessioned 2020-06-29T23:23:10Z
dc.date.available 2020-06-29T23:23:10Z
dc.date.issued 2018-07-02
dc.description.abstract <p>The detailed behavior of the in-plane infrared-active vibrational modes has been determined in <em>A</em>Fe2As2 (<em>A</em>=Ca, Sr, and Ba) above and below the structural and magnetic transitions at TN=172, 195, and 138 K, respectively. Above TN, two infrared-active Eu modes are observed. In all three compounds, below TN, the low-frequency Eu mode is observed to split into upper and lower branches; with the exception of the Ba material, the oscillator strength across the transition is conserved. In the Ca and Sr materials, the high-frequency Eu mode splits into an upper and a lower branch; however, the oscillator strengths are quite different. Surprisingly, in both the Sr and Ba materials, below TN the upper branch appears to be either very weak or totally absent, while the lower branch displays an anomalous increase in strength. The frequencies and atomic characters of the lattice modes at the center of the Brillouin zone have been calculated for the high-temperature phase for each of these materials. The high-frequency Eu mode does not change in position or character across this series of compounds. Below TN, the Eu modes are predicted to split into features of roughly equal strength. We discuss the possibility that the anomalous increase in the strength of the lower branch of the high-frequency mode below TN in the Sr and Ba compounds, and the weak (silent) upper branch, may be related to the orbital ordering and a change in the bonding between the Fe and As atoms in the magnetically ordered state.</p>
dc.identifier archive/lib.dr.iastate.edu/ameslab_manuscripts/434/
dc.identifier.articleid 1430
dc.identifier.contextkey 15049296
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath ameslab_manuscripts/434
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/7381
dc.language.iso en
dc.relation.ispartofseries BNL-205789-2018-JAAM; IS-J 9712
dc.source.bitstream archive/lib.dr.iastate.edu/ameslab_manuscripts/434/IS_J_9712.pdf|||Sat Jan 15 00:16:04 UTC 2022
dc.source.uri 10.1103/PhysRevB.98.035103
dc.subject.disciplines Condensed Matter Physics
dc.subject.disciplines Materials Science and Engineering
dc.title Vibrational anomalies in AFe2As2 (A=Ca, Sr, and Ba) single crystals
dc.type article
dc.type.genre article
dspace.entity.type Publication
relation.isAuthorOfPublication c5a8128b-7d98-4b8f-92d7-b1385e345713
relation.isOrgUnitOfPublication 25913818-6714-4be5-89a6-f70c8facdf7e
relation.isOrgUnitOfPublication 4a05cd4d-8749-4cff-96b1-32eca381d930
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