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Lattice dynamics of the hybrid improper ferroelectrics (Ca,Sr)3Ti2 O7

Publication ,  Journal Article
Bansal, D; Niedziela, JL; He, X; Lanigan-Atkins, T; Said, A; Alatas, A; Abernathy, DL; Ren, Y; Gao, B; Cheong, SW; Delaire, O
Published in: Physical Review B
December 6, 2019

The structure and lattice dynamics of the hybrid improper ferroelectric compound Ca3-xSrxTi2O7 (for x=0,0.6, and 0.9) have been studied with a combination of diffraction, inelastic scattering experiments, Raman spectroscopy, and calorimetry measurements, as well as first-principles simulations. Using inelastic neutron scattering, we have measured the phonon density of states (DOS) for x=0.9, which revealed a strong broadening but little change in phonon energies on heating from 10 K to 728 K across the ferroelectric phase transition temperature, TFE. Using inelastic X-ray scattering, the momentum-resolved phonon dispersions were measured from 80 K to 950 K on a single crystal (for x=0.6), and also revealed a strong phonon broadening but a small energy shift for acoustic modes on heating across TFE. Our Raman measurements (for x=0.6) showed robust rotational and oxygen breathing modes but soft tilt modes, consistent with previous measurements on similar compounds. Our density functional calculations achieve good agreement with both the phonon DOS and dispersions measured. We did not observe any unusual quadratic dispersion for c-polarized transverse acoustic modes, at odds with a recently predicted quasi-2D character, for either undoped (x=0) or doped (x=0.6) compounds.

Duke Scholars

Published In

Physical Review B

DOI

EISSN

2469-9969

ISSN

2469-9950

Publication Date

December 6, 2019

Volume

100

Issue

21

Related Subject Headings

  • 51 Physical sciences
  • 40 Engineering
  • 34 Chemical sciences
 

Citation

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Bansal, D., Niedziela, J. L., He, X., Lanigan-Atkins, T., Said, A., Alatas, A., … Delaire, O. (2019). Lattice dynamics of the hybrid improper ferroelectrics (Ca,Sr)3Ti2 O7. Physical Review B, 100(21). https://doi.org/10.1103/PhysRevB.100.214304
Bansal, D., J. L. Niedziela, X. He, T. Lanigan-Atkins, A. Said, A. Alatas, D. L. Abernathy, et al. “Lattice dynamics of the hybrid improper ferroelectrics (Ca,Sr)3Ti2 O7.” Physical Review B 100, no. 21 (December 6, 2019). https://doi.org/10.1103/PhysRevB.100.214304.
Bansal D, Niedziela JL, He X, Lanigan-Atkins T, Said A, Alatas A, et al. Lattice dynamics of the hybrid improper ferroelectrics (Ca,Sr)3Ti2 O7. Physical Review B. 2019 Dec 6;100(21).
Bansal, D., et al. “Lattice dynamics of the hybrid improper ferroelectrics (Ca,Sr)3Ti2 O7.” Physical Review B, vol. 100, no. 21, Dec. 2019. Scopus, doi:10.1103/PhysRevB.100.214304.
Bansal D, Niedziela JL, He X, Lanigan-Atkins T, Said A, Alatas A, Abernathy DL, Ren Y, Gao B, Cheong SW, Delaire O. Lattice dynamics of the hybrid improper ferroelectrics (Ca,Sr)3Ti2 O7. Physical Review B. 2019 Dec 6;100(21).

Published In

Physical Review B

DOI

EISSN

2469-9969

ISSN

2469-9950

Publication Date

December 6, 2019

Volume

100

Issue

21

Related Subject Headings

  • 51 Physical sciences
  • 40 Engineering
  • 34 Chemical sciences