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Title: Phonon density of states of single-crystal SrF e 2 A s 2 across the collapsed phase transition at high pressure

Abstract

To help our understanding of the structural and superconducting transitions in ferropnictides, partial phonon density of states (PDOS) of iron in a single-crystal SrFe2As2 pnictide have been investigated from both out-ofplane and in-plane polarizations with respect to the basal plane of the crystal structure using nuclear resonant inelastic x-ray scattering in a high-pressure diamond anvil cell at ambient temperature. The partial PDOS of iron in the pnictide crystal changes dramatically at approximately 8 GPa, which can be associated with the tetragonal(T)tocollapsedtetragonal(CT)isostructuraltransitionasevidencedinhigh-pressurex-raydiffraction measurements and theoretic calculations. Across the T-CT phase transition, analysis of the PDOS spectra shows a rapid stiffening of the optical phonon modes and a dramatic increase of the Lamb-M¨ossbauer factor (fLM) and mean force constant which can be associated with the rapid decrease of the c axis and the anomalous expansion of the a axis. Theoretically calculated Fe partial PDOS and lattice parameters of SrFe2As2 further reveal the strong correlation between the lattice parameters and phonons. Our results show that the T-CT transition can induce significant changes in the vibrational, elastic, and thermodynamic properties of SrFe2As2 single crystal at high pressure.

Authors:
; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); National Natural Science Foundation of China (NNSFC)
OSTI Identifier:
1390803
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B; Journal Volume: 94; Journal Issue: 1
Country of Publication:
United States
Language:
English

Citation Formats

Wang, Y. Q., Lu, P. C., Wu, J. J., Liu, J., Wang, X. C., Zhao, J. Y., Bi, W., Alp, E. E., Park, C. Y., Popov, D., Jin, C. Q., Sun, J., and Lin, J. F.. Phonon density of states of single-crystal SrFe2As2 across the collapsed phase transition at high pressure. United States: N. p., 2016. Web. doi:10.1103/PhysRevB.94.014516.
Wang, Y. Q., Lu, P. C., Wu, J. J., Liu, J., Wang, X. C., Zhao, J. Y., Bi, W., Alp, E. E., Park, C. Y., Popov, D., Jin, C. Q., Sun, J., & Lin, J. F.. Phonon density of states of single-crystal SrFe2As2 across the collapsed phase transition at high pressure. United States. doi:10.1103/PhysRevB.94.014516.
Wang, Y. Q., Lu, P. C., Wu, J. J., Liu, J., Wang, X. C., Zhao, J. Y., Bi, W., Alp, E. E., Park, C. Y., Popov, D., Jin, C. Q., Sun, J., and Lin, J. F.. Fri . "Phonon density of states of single-crystal SrFe2As2 across the collapsed phase transition at high pressure". United States. doi:10.1103/PhysRevB.94.014516.
@article{osti_1390803,
title = {Phonon density of states of single-crystal SrFe2As2 across the collapsed phase transition at high pressure},
author = {Wang, Y. Q. and Lu, P. C. and Wu, J. J. and Liu, J. and Wang, X. C. and Zhao, J. Y. and Bi, W. and Alp, E. E. and Park, C. Y. and Popov, D. and Jin, C. Q. and Sun, J. and Lin, J. F.},
abstractNote = {To help our understanding of the structural and superconducting transitions in ferropnictides, partial phonon density of states (PDOS) of iron in a single-crystal SrFe2As2 pnictide have been investigated from both out-ofplane and in-plane polarizations with respect to the basal plane of the crystal structure using nuclear resonant inelastic x-ray scattering in a high-pressure diamond anvil cell at ambient temperature. The partial PDOS of iron in the pnictide crystal changes dramatically at approximately 8 GPa, which can be associated with the tetragonal(T)tocollapsedtetragonal(CT)isostructuraltransitionasevidencedinhigh-pressurex-raydiffraction measurements and theoretic calculations. Across the T-CT phase transition, analysis of the PDOS spectra shows a rapid stiffening of the optical phonon modes and a dramatic increase of the Lamb-M¨ossbauer factor (fLM) and mean force constant which can be associated with the rapid decrease of the c axis and the anomalous expansion of the a axis. Theoretically calculated Fe partial PDOS and lattice parameters of SrFe2As2 further reveal the strong correlation between the lattice parameters and phonons. Our results show that the T-CT transition can induce significant changes in the vibrational, elastic, and thermodynamic properties of SrFe2As2 single crystal at high pressure.},
doi = {10.1103/PhysRevB.94.014516},
journal = {Physical Review B},
number = 1,
volume = 94,
place = {United States},
year = {Fri Jul 01 00:00:00 EDT 2016},
month = {Fri Jul 01 00:00:00 EDT 2016}
}