Infrared dispersion in SrTi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>at high temperature

Servoin, J. L.; Luspin, Y.; Gervais, F.

doi:10.1103/physrevb.22.5501

Cited by 179 publications

(83 citation statements)

References 31 publications

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“…All these fits lead to a conclusion that the soft mode frequency hardens by 6 cm −1 when the field is applied. Similar frequency shift of the soft mode was observed in the temperature dependence upon heating by 60 K. 11 The soft mode is heavily damped ͑␥ Ϸ 95-115 cm −1 ͒ and the fit is slightly improved if the damping decreases with the field ͑by 2 -5 cm −1 ͒. Other parameters ͑ 0 Ϸ 90 cm −1 , B Ϸ 2.5ϫ 10 6 cm −2 ͒ are in reasonable agreement with their values reported for single crystals.…”

supporting

confidence: 64%

“…The error of the determination of the permittivity value is about 30%. Note that the low-frequency value of the permittivity ͑Ϸ370͒ and the soft mode frequency ͑Ϸ90 cm −1 ͒ of the thin film are close to the values found in STO single crystals, 11 giving evidence of a good quality of our film. The damping of the soft mode is found to be rather strong ͑95-115 cm −1 ͒; this is probably due to the inhomogeneous broadening which is frequently observed in thin films.…”

mentioning

confidence: 52%

“…Other parameters ͑ 0 Ϸ 90 cm −1 , B Ϸ 2.5ϫ 10 6 cm −2 ͒ are in reasonable agreement with their values reported for single crystals. 7,11 To summarize, we have demonstrated the field-induced tunability of the dielectric properties of STO thin films in the MHz and THz frequency ranges. We have shown that the observed modulation is due to the soft mode hardening upon applied electric field.…”

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confidence: 99%

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Dielectric tunability of SrTiO3 thin films in the terahertz range

Kužel

Kadlec

Němec

et al. 2006

Applied Physics Letters

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We have developed an interdigited electrode structure for applying a static electric field to a ferroelectric thin film, which enables nearly full transmission of a perpendicularly polarized terahertz wave. This approach has been used to determine the electric field dependence of the complex permittivity of a SrTiO3 thin film on a sapphire substrate up to about 2THz employing time-domain terahertz spectroscopy. We have demonstrated up to 10% variation of the film permittivity at 300GHz at room temperature induced by an applied electric field of 100kV∕cm. No dielectric dispersion is observed between 1MHz and about 500GHz. The field-induced changes are attributed to soft mode hardening.

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confidence: 64%

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confidence: 52%

mentioning

confidence: 99%

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Dielectric tunability of SrTiO3 thin films in the terahertz range

Kužel

Kadlec

Němec

et al. 2006

Applied Physics Letters

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“…For 0.001 ≤ x ≤ 0.02, the band-structure value [18] of the Fermi energy, E F , ranges from 0.02 to 0.1 eV, relative to the bottom of the lowest t 2g band, which coincides with the energy of the relevant longitudinal optical phonon,hω LO = 0.1 eV [19,20]. This is a difficult parameter range to describe theoretically where none of the usual approximations, i.e.,hω LO /E F ≪ 1 norhω LO /E F ≫ 1 are applicable.…”

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confidence: 99%

Electron-Phonon Interaction and Charge Carrier Mass Enhancement inSrTiO3

Mechelen¹,

Marel²,

Grimaldi³

et al. 2008

Phys. Rev. Lett.

198

213

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We report a comprehensive THz, infrared and optical study of Nb doped SrTiO3 as well as DC conductivity and Hall effect measurements. Our THz spectra at 7 K show the presence of a very narrow (< 2 meV) Drude peak, the spectral weight of which shows approximately a factor of three enhancement of the band mass for all carrier concentrations. The missing spectral weight is regained in a broad 'mid-infrared' band which originates from electron-phonon coupling. We find no evidence of a particularly large electron-phonon coupling that would result in small polaron formation. Analysis of the results yields an electron-phonon coupling parameter of an intermediate strength, α ≈ 4.PACS numbers: 71.38.-k, 72.20.-i, 78.20.-e Electron-phonon coupling in the perovskites is a subject of much recent interest due to the controversy over its relevance in the phenomena of multiferroicity, ferroelectricity, superconductivity and colossal magnetoresistance [1,2,3,4,5]. Despite much progress, full understanding of the physics of electron-phonon coupling in perovskites is still lacking because of additional crystallographic complexities of many materials involved (breathing, tilting and rotational distortions, ferroelectric symmetry breaking), magnetism, complex electronic effects (strong correlations), and also because of the lack of high-accuracy spectroscopic measurements specifically designed to probe electron-phonon coupling.With this in mind, we have studied a prototypical perovskite oxide, SrTi 1−x Nb x O 3 with 0 ≤ x ≤ 0.02. SrTiO 3 is an insulator (∆ = 3.25 eV) with the conduction band formed by the Ti 3d states. These are split by the crystal field so that the three t 2g states become occupied when the material is electron-doped by substituting pentavalent Nb for tetravalent Ti. For 0.0005 ≤ x ≤ 0.02 SrTi 1−x Nb x O 3 becomes superconducting at a T c of typically ∼ 0.3 K [6,7], and at most 1.2 K [5]. Characterized by the threefold degeneracy of the conduction bands and the high lattice polarizability, electron doped SrTiO 3 provides a perfect opportunity for the study of electronphonon coupling and polaron formation in an archetypal perovskite [8,9].

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“…The LST relation is playing a crucial role in the understanding of the physics of ferroelectric materials [12]. For example, lattice instabilities in ferroelectric [13] perovskite titanates such as SrTiO 3 and ðBa; SrÞTiO 3 [14,15] across the phase transition affect static dielectric constants and phonon modes. The LST relation has been expanded previously to include situations where multiple branches of phonon modes occur, and the role of poles and zeros in the complex plane to describe the dielectric response functions was identified [16][17][18].…”

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confidence: 99%

Coordinate-Invariant Lyddane-Sachs-Teller Relationship for Polar Vibrations in Materials with Monoclinic and Triclinic Crystal Systems

Schubert

2016

Phys. Rev. Lett.

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A coordinate-invariant generalization of the Lyddane-Sachs-Teller relation is presented for polar vibrations in materials with monoclinic and triclinic crystal systems. The generalization is derived from an eigendielectric displacement vector summation approach, which is equivalent to the microscopic Born-Huang description of polar lattice vibrations in the harmonic approximation. An expression for a general oscillator strength is also described for materials with monoclinic and triclinic crystal systems. A generalized factorized form of the dielectric response characteristic for monoclinic and triclinic materials is proposed. The generalized Lyddane-Sachs-Teller relation is found valid for monoclinic beta-Ga2O3, where accurate experimental data became available recently from a comprehensive generalized ellipsometry investigation [Phys. Rev. B 93, 125209 (2016)]. Data for triclinic crystal systems can be measured by generalized ellipsometry as well, and are anticipated to become available soon and results can be compared with the generalized relations presented here.

Funding Agencies|National Science Foundation (NSF) through the Center for Nanohybrid Functional Materials [EPS 1004094]; Nebraska Materials Research Science and Engineering Center [DMR 1420645]; [CMMI 1337856]

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Infrared dispersion in SrTiO3at high temperature

Cited by 179 publications

References 31 publications

Dielectric tunability of SrTiO3 thin films in the terahertz range

Dielectric tunability of SrTiO3 thin films in the terahertz range

Electron-Phonon Interaction and Charge Carrier Mass Enhancement inSrTiO3

Coordinate-Invariant Lyddane-Sachs-Teller Relationship for Polar Vibrations in Materials with Monoclinic and Triclinic Crystal Systems

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