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Type: Artigo de periódico
Title: Soft-mode Spectroscopy In Cubic Batio3 By Hyper-raman Scattering
Author: Vogt H.
Sanjurjo J.A.
Rossbroich G.
Abstract: Hyper-Raman scattering from cubic BaTiO3 is studied to clarify the controversies about the low-frequency dielectric response in this material. Applying the fluctuation-dissipation theorem, we obtain the imaginary part ε′′(Ω) of the dielectric function in the wave-number range from 3 to 150 cm-1. ε′′(Ω) can be adequately described by a classical single-oscillator dispersion formula. In approaching the Curie temperature, we find a continuous decrease of the mode frequency Ω0. The relative damping constant γΩ0 exceeds 2, so that the mode may be referred to as intermediate between oscillator and relaxator. Because of the high damping ε′′(Ω) can be formally written as the sum of two overdamped oscillator contributions. This would lead to the concept of a soft-mode saturation and an extra dispersion mechanism as has been recently inferred from the far-infrared reflectivity spectrum. However, we do not find any evidence for this mode splitting and, so far, regard it as artificial. © 1982 The American Physical Society.
Rights: aberto
Identifier DOI: 10.1103/PhysRevB.26.5904
Date Issue: 1982
Appears in Collections:Unicamp - Artigos e Outros Documentos

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