Adjusting Poles and Zeros of Dielectric Dispersion to Fit Reststrahlen of Pr<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Cl</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>and La<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Cl</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:ms

Berreman, Dwight W.; Unterwald, F. C.

doi:10.1103/physrev.174.791

Cited by 173 publications

(88 citation statements)

References 12 publications

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“…This fitting procedure infers a splitting of the longitudinal and transverse eigenfrequencies, ω L and ω T , and the corresponding damping constants, Γ L and Γ T . 30 The resulting curves describe the measured reflectivity down to 100 cm −1 very well, without assuming an additional contribution of free charge carriers. A representative result of these fits is shown by the solid line in the upper panel of Fig.…”

Section: Resultsmentioning

confidence: 76%

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
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A detailed investigation of phonon excitations and charge carrier dynamics in single crystals of Fe1−xCuxCr2S4 (x = 0, 0.2, 0.4, 0.5) has been performed by using infrared spectroscopy. In FeCr2S4 the phonon eigenmodes are strongly affected by the onset of magnetic order. Despite enhanced screening effects, a continuous evolution of the phonon excitations can be observed in the doped compounds with x = 0.2 (metallic) and x = 0.4, 0.5 (bad metals), but the effect of magnetic ordering on the phonons is strongly reduced compared to x = 0. The Drude-like charge-carrier contribution to the optical conductivity in the doped samples indicates that the colossal magneto-resistance effect results from the suppression of spin-disorder scattering.

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Section: Resultsmentioning

confidence: 76%

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
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“…[22][23][24] The best-fit parameters are given in the upper part of Table II. The overall fit is quite reasonable.…”

Section: Infrared Reflectivity and Dielectric Dispersionmentioning

confidence: 99%

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2O
Moret
¹
,
Zallen
²
,
Newnham
³

et al. 1998
Phys. Rev. B
60
6
29
0
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Experimental studies were carried out on infrared-active phonons in the Aurivillius ferroelectric SrBi 2 Ta 2 O 9 ͑SBT͒, using reflectivity measurements ͑down to 200 cm Ϫ1 ͒ and transmission measurements ͑down to 100 cm Ϫ1 ͒ on crystals, pellets, and thin films. An analysis was done of the contrasting consequences of the competing orthorhombic and pseudotetragonal symmetries in SBT. Reflectivity results for light polarized in the ab plane show that the anisotropy in this plane is small in the frequency range from 300 to 1200 cm Ϫ1 , indicating the influence of the approximate tetragonal symmetry. Dielectric dispersion properties were derived for this polarization (EЌc) in this frequency range. The transverse-optical ͑TO͒ and longitudinal-optical ͑LO͒ frequencies corresponding to the dominant EЌc band are 613 and 773 cm Ϫ1 , respectively. This strong, highfrequency band arises from a mode dominated by the motion of the oxygen sublattice; its TO and LO frequencies yield an oxygen-ion Szigeti effective charge of Ϫ1.5e. Frequency estimates for the TO ͑LO͒ pairs of other strong bands are 188͑330͒ and 334(451) cm Ϫ1 for EЌc, and 610͑675͒ and 780(815) cm Ϫ1 for Eʈc. In addition to the main infrared bands, the main Raman bands of SBT are also reported.

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“…V C). In the case of a scalar dielectric function, an asymmetric line shape [or, more precisely, a non-Lorentzian line shape of ε(ω)] can be described using a factorized four-parameter model 41,56,57 which employs two different values γ T,i and γ L,i for the damping of the i-th oscillator at the transverse and longitudinal eigenfrequencies. This mimics an approximately quadratic frequency dependence of the damping γ = γ(ω).…”

Section: B Asymmetric Oscillator Modelmentioning

confidence: 99%

Infrared-active phonon modes in monoclinic multiferroicMnWO4

et al. 2014

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We report on polarized infrared reflectivity measurements of multiferroic, monoclinic MnWO4 between 10 K and 295 K. All five non-vanishing components of the dielectric tensor have been determined in the frequency range of the phonons. All infrared-active phonon modes (7 Au modes and 8 Bu modes) are unambiguously identified. In particular the strongest Bu modes have been overlooked in previous studies, in which the monoclinic symmetry was neglected in the analysis. The combined analysis of reflectance data measured in different experimental geometries (Rac and Rp) is particularly helpful for a proper identification of the Bu modes. Using a generalized Drude-Lorentz model, we determine the temperature dependence of the phonon parameters, including the orientation of the Bu modes within the ac plane. The phonon parameters and their temperature dependence were discussed controversially in previous studies, which did not include a full polarization analysis. Our data do not confirm any of the anomalies reported above 20 K. However, in the paramagnetic phase we find a drastic reduction of the spectral weights of the weakest Au mode and of the weakest Bu mode with increasing temperature. Below 20 K, the parameters of the Au phonon modes for E b show only subtle changes, which demonstrate a finite but weak coupling between lattice dynamics and magnetism in MnWO4. A quantitative comparison of our infrared data with the quasi-static dielectric constant ε b yields a rough estimate for the oscillator strength ∆εem 0.02 of a possible electromagnon for E b. Furthermore, we report on a Kramers-Kronig-consistent model which is able to describe non-Lorentzian line shapes in compounds with monoclinic symmetry.

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Adjusting Poles and Zeros of Dielectric Dispersion to Fit Reststrahlen of PrCl3and LaCl3

Cited by 173 publications

References 12 publications

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
View full text Add to dashboard Cite

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
View full text Add to dashboard Cite

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2O
Moret
¹
,
Zallen
²
,
Newnham
³

et al. 1998
Phys. Rev. B
60
6
29
0
View full text Add to dashboard Cite

Infrared-active phonon modes in monoclinic multiferroicMnWO4

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Adjusting Poles and Zeros of Dielectric Dispersion to Fit Reststrahlen of PrCl3and LaCl3

Cited by 173 publications

References 12 publications

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4Rudolf1, Pucher2, Mayr3 et al. 2005Phys. Rev. B16190View full textAdd to dashboardCite

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4Rudolf1, Pucher2, Mayr3 et al. 2005Phys. Rev. B16190View full textAdd to dashboardCite

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2OMoret1, Zallen2, Newnham3 et al. 1998Phys. Rev. B606290View full textAdd to dashboardCite

Infrared-active phonon modes in monoclinic multiferroicMnWO4

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About

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
View full text Add to dashboard Cite

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
View full text Add to dashboard Cite

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2O
Moret
¹
,
Zallen
²
,
Newnham
³

et al. 1998
Phys. Rev. B
60
6
29
0
View full text Add to dashboard Cite