Temperature dependence of plasmons in Nb-doped<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">SrTiO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Gervais, F.; Servoin, J. L.; Baratoff, A.; Bednorz, J. G.; Binnig, G.

doi:10.1103/physrevb.47.8187

Cited by 121 publications

(97 citation statements)

References 29 publications

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“…The Hall carrier concentrations were 0.105%, 0.196%, 0.875% and 2.00% at 7 K, which were within 5 % of those measured by the wavelengthdispersive X-ray spectroscopy, and within 12 % of the Nb concentration specified by the supplier (0.1%, 0.2%, 1.0% and 2.0%, respectively, Crystec, Berlin). Compared to earlier measurements [10,11,12,13,14], we expand the spectral range further into the far-infrared and THz band. Fig.…”

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confidence: 89%

Electron-Phonon Interaction and Charge Carrier Mass Enhancement inSrTiO3

Mechelen¹,

Marel²,

Grimaldi³

et al. 2008

Phys. Rev. Lett.

200

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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confidence: 89%

Electron-Phonon Interaction and Charge Carrier Mass Enhancement inSrTiO3

Mechelen¹,

Marel²,

Grimaldi³

et al. 2008

Phys. Rev. Lett.

200

213

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“…Insulating SrTiO 3 has a perovskite structure and manifests a metal-insulator transition at room temperature around a doping of 0.002% La or Nb per unit cell [13]. At low doping concentrations, between 0.003% and 3%, strontium titanate reveals a superconducting phase transition [14] below 0.7 K. Various optical experiments [13,[15][16][17][18][19] show a mid-infrared band in the normal state optical conductivity of doped SrTiO 3 which is often explained by polaronic behavior. In the recently observed optical conductivity spectra of Ref.…”

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confidence: 99%

Many-body large polaron optical conductivity inSrTi1−xNbxO3

et al. 2010

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Recent experimental data on the optical conductivity of niobium doped SrTiO3 are interpreted in terms of a gas of large polarons with effective coupling constant α ef f ≈ 2. The theoretical approach takes into account many-body effects, the electron-phonon interaction with multiple LOphonon branches, and the degeneracy and the anisotropy of the Ti t2g conduction band. Based on the Fröhlich interaction, the many-body large-polaron theory provides an interpretation for the essential characteristics, except -interestingly -for the unexpectedly large intensity of a peak at ∼ 130 meV, of the observed optical conductivity spectra of SrTi1−xNbxO3 without any adjustment of material parameters.

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“…Most of the literature so far has been dedicated to n-type SrTiO 3 , [21][22][23][24][25] and only a limited number of papers have addressed optical properties of n-type BaTiO 3 . 26, 27 Crandles et al studied highly reduced SrTiO 3−δ by using optical spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Doping and temperature-dependent optical properties of oxygen-reducedBaTiO3−δ

et al. 2010

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We report on optical properties of reduced BaTiO 3−δ at different doping levels including insulating and metallic samples. In all the samples, including metallic one, we observe structural phase transitions from the changes of the infrared active phonon modes. Metallic ground state is confirmed by the Drude-type low-frequency optical reflectance. Similar to SrTiO 3−δ we find that the mid-infrared absorption band in BaTiO 3−δ appears and grows with an increase in the oxygen vacancy concentration. Upon decrease in temperature from 300 K, the mid-infrared band shifts slightly to higher frequency and evolves into two bands: the existing band and a new and smaller band at lower frequency. The appearance of the new and smaller band seems to be correlated with the structural phase transitions.

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Temperature dependence of plasmons in Nb-dopedSrTiO3

Cited by 121 publications

References 29 publications

Electron-Phonon Interaction and Charge Carrier Mass Enhancement inSrTiO3

Electron-Phonon Interaction and Charge Carrier Mass Enhancement inSrTiO3

Many-body large polaron optical conductivity inSrTi1−xNbxO3

Doping and temperature-dependent optical properties of oxygen-reducedBaTiO3−δ

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