Far IR spectra of ferroelectric Rochelle Salt and sodium ammonium tartrate

Gerbaux, X.; Hadni, A.; Kitade, Atsuo

doi:10.1002/pssa.2211150229

Cited by 7 publications

(1 citation statement)

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“…Early far-infrared (FIR) measurements [25] on Rochelle salt showed that a thin film has higher transmission than a thick film, and that extra peaks appear in thin films. Recent FIR measurements [26] on PbTiO 3 and PZT film have been carried out, but there was no discussion of size or surface effects.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of ferroelectric thin films described by the transverse Ising model

Wang

Smith

1996

J. Phys.: Condens. Matter

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The dynamic properties of thin films described by the Ising model in a transverse field (TIM) have been studied under the random-phase approximation. The frequencies of soft modes and surface modes have been obtained. For films with reduced surface interaction (compared to the bulk), the soft mode corresponds to a surface-like mode in the ferroelectric phase but to a bulk-like mode in the paraelectric phase. Conversely, for films with an enhanced surface interaction, the soft mode is a bulk-like mode in the ferroelectric phase and a surfacelike mode in the paraelectric phase. The number of surface-like modes in the ferroelectric phase can be greater than one; the number increases as the temperature approaches the Curie temperature, and does not depend on the in-plane wavevector for a given temperature in the ferroelectric phase. However, there is only one surface-like mode in the paraelectric phase, and its character becomes bulk-like at large wavevector. The surface modes can be clearly seen from the frequency dependence of the dynamic susceptibility; the surface mode pole increases in strength with decreasing film thickness. The frequency dependences of optical reflectivity coefficients have also been obtained. The reflection peaks due to the surface modes lie below the bulk reststrahl band in the ferroelectric phase of films with reduced surface ferroelectricity, and also in the paraelectric phase of films with enhanced surface ferroelectricity; otherwise, they lie within the reststrahl band.

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Section: Introductionmentioning

confidence: 99%