Soft-mode spectroscoopy of epitaxial BaTiO{sub 3}/SrTiO{sub 3} superlattices.
It is demonstrated that soft modes in 240 nm think BaTiO{sub 3}/SrTiO{sub 3} ferroelectric superlattices can be probed by infrared reflectivity measurements, which allows us to estimate the intrinsic in-plane dielectric constants of such thin superlattice slabs. The infrared reflectance spectrum of the (BaTiO{sub 3}){sub 8}/(SrTiO{sub 3}){sub 4} superlattice epitaxially grown a DyScO{sub 3} single-crystal substrate reveals a strong polar mode with a transverse optic frequency of about 70 cm{sup -1} and moderate damping (about 30 cm{sup -1}). Our analysis of the experimental results is combined with the first-principles based theoretical evaluation of optical polar modes in a model system representing the 60-atom periodic superlattice unit cell. This hybrid approach suggests that the observed soft mode is associated with a Slater-type polar mode confined mostly in the SrTiO{sub 3} component layer.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 994057
- Report Number(s):
- ANL/MSD/JA-67972; TRN: US201024%%248
- Journal Information:
- Phys. Rev. B, Vol. 82, Issue Dec. 2010
- Country of Publication:
- United States
- Language:
- ENGLISH
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