The midinfrared absorption in RTiO3 perovskites (R = La, Ce, Pr, Nd, Sm, Gd)

Crandles, D. A.; Timusk, T.; Garrett, J.D.; Greedan, J. E.

doi:10.1016/0921-4534(92)90491-t

Cited by 65 publications

(34 citation statements)

References 20 publications

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“…This raises the question of the origin of absorption with an onset around 0.7 eV observed in reflectivity measurements. [4][5][6] We attribute this onset to transitions between self-trapped holes and the LHB. 15 The presence of self-trapped holes in rare-earth titanates has been inferred from thermally activated ptype hopping conductivity.…”

Section: Discussionmentioning

confidence: 99%

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Determination of the Mott-Hubbard gap inGdTiO3

et al. 2015

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The band gaps of rare-earth titanates are commonly reported to be 0.2-0.7 eV. These values are based on optical reflectivity measurements, from which the onset of optical absorption is derived. Here we report experimental and theoretical results on GdTiO3 (GTO) indicating that the gap is significantly larger. Photoluminescence (PL) measurements show a strong peak near 1.8 eV, consistent with an observed onset in PL excitation (PLE) at about the same energy. First-principles calculations, based either on density functional theory (DFT) with a hybrid functional or on DFT+U , consistently show that the gap is close to 2 eV. We also propose an interpretation of the previously reported optical absorption spectra. Given the similarities in electronic structure between the rareearth titanates, our results for GTO have repercussions for the other members of the series. The results also affect the design of complex-oxide heterostructures involving these materials.

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Section: Discussionmentioning

confidence: 99%

“…Previous efforts to determine the Mott-Hubbard gap of GTO were based on optical absorption obtained by Kramers-Kronig analysis of reflectivity data on bulk crystals 4 or thin films grown on (LaAlO 3 ) 0.3 (Sr 2 AlTaO 6 ) 0.7 (LSAT), 5 and from transmission spectroscopy of films grown on SrLaGaO 4 .…”

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confidence: 99%

Determination of the Mott-Hubbard gap inGdTiO3

et al. 2015

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“…Doping driven metal-insulator transitions in threedimensional perovskites La 1−x Sr x TiO 3−␦ have been extensively explored in the past decade ͑Maeno et al ., 1990;Crandles et al, 1992;Sunstrom et al, 1992;Tokura et al, 1993;Yasumoto, 1997a, 1997b;Onoda and Kohno, 1998;Hays et al, 1999͒. The electronic properties of the La 1−x Sr x TiO 3 series is governed by the t 2g subset of the 3d orbitals.…”

Section: Doping Driven Metal-insulator Transitionmentioning

confidence: 99%

Electronic structure calculations with dynamical mean-field theory

et al. 2006

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A review of the basic ideas and techniques of the spectral density-functional theory is presented. This method is currently used for electronic structure calculations of strongly correlated materials where the one-electron description breaks down. The method is illustrated with several examples where interactions play a dominant role: systems near metal-insulator transitions, systems near volume collapse transitions, and systems with local moments.

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“…6 10 21 22 The only work providing temperature-dependent data in the FIR region to our knowledge is ref. 6, but unfortunately the authors do not provide any analysis of the observed phonon modes.…”

Section: Phonon Modesmentioning

confidence: 99%

“…6, 7, 9, and 10, a quantitative evaluation of the Mott-Hubbard gap energy E g was performed by using a simple linear extrapolation in the σ'(ν) plot. Roomtemperature values of E g = 20 meV, 6 0.1 eV, 7 10 and 0.2 eV 9 were reported, the variation reflecting uncertainties due to the choice of the section of the spectrum used for the extrapolation and possible differences of stoichiometry of the samples. Only in ref.…”

Section: Figmentioning

confidence: 99%

Dielectric properties and dynamical conductivity ofLaTiO3: From dc to optical frequencies

et al. 2003

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We provide a complete and detailed characterization of the temperature-dependent response to ac electrical fields of LaTiO 3 , a Mott-Hubbard insulator close to the metal-insulator transition. We present combined dc, broadband dielectric, mm-wave, and infrared spectra of ac conductivity and dielectric constant, covering an overall frequency range of 17 decades. The dc and dielectric measurements reveal information on the semiconducting charge-transport properties of LaTiO 3 , indicating the importance of Anderson localization, and on the dielectric response due to ionic polarization. In the infrared region, the temperature dependence of the phonon modes gives strong hints for a structural phase transition at the magnetic ordering temperature. In addition, a gap-like electronic excitation following the phonon region is analyzed in detail. We compare the results to the soft-edge behavior of the optical spectra characteristic for Mott-Hubbard insulators. Overall a consistent picture of the charge-transport mechanisms in LaTiO 3 emerges.

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The midinfrared absorption in RTiO3 perovskites (R = La, Ce, Pr, Nd, Sm, Gd)

Cited by 65 publications

References 20 publications

Determination of the Mott-Hubbard gap inGdTiO3

Determination of the Mott-Hubbard gap inGdTiO3

Electronic structure calculations with dynamical mean-field theory

Dielectric properties and dynamical conductivity ofLaTiO3: From dc to optical frequencies

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