Publisher's Note: Temperature- and doping-dependent optical absorption in the small-polaron system 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Pr</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Ca</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>MnO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>
 [Phys. Rev. B 
<b>92</b>
, 035145 (2015)]

Mildner, Stephanie; Hoffmann, J.; Blöchl, Peter E.; Techert, Simone; Jooß, Christian

doi:10.1103/physrevb.94.159902

Cited by 9 publications

(26 citation statements)

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“…This free parameter is determined by experimental X-ray photoelectron spectroscopy (XPS). The resulting description is verified by comparison with electron energy-loss near-edge structure (ELNES) and the X-ray absorption near-edge structure (XANES) 42 , as well as measurements of optical absorption 43 . The density-functional calculations in turn serve to determine a minimal model, which puts the focus on the mechanisms for the polaron order and the effects of varying correlations on the states forming the band gap in manganites.…”

Section: 22mentioning

confidence: 78%

Electronic structure of Pr1−xCaxMnO3

et al. 2017

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The electronic structure of Pr1−xCaxMnO3 has been investigated using a combination of firstprinciples calculations, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), electron-energy loss spectroscopy (EELS), and optical absorption. The full range of compositions, x = 0, 1/2, 1, and a variety of magnetic orders have been covered. Jahn-Teller as well as Zener polaron orders are considered. The free parameters of the local hybrid density functionals used in this study has been determined by comparison with measured XPS spectra. A model Hamiltonian, valid for the entire doping range, has been extracted. A simple local-orbital picture of the electronic structure for the interpretation of experimental spectra is provided. The comparison of theoretical calculations and different experimental spectra provide a detailed and consistent picture of the electronic structure. The large variations of measured optical absorption spectra are traced back to the coexistence of magnetic orders respectively to the occupation of local orbitals. A consistent treatment of the Coulomb interaction indicate a partial cancellation of Coulomb parameters and support the dominance of the electron-phonon coupling.

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Section: 22mentioning

confidence: 78%

Electronic structure of Pr1−xCaxMnO3

et al. 2017

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“…Symmetry-lowering distortions in the crystal or oddparity vibrations are unable to explain the observed strong absorption in Figure 1, which reaches 25%-30% of that of the charge-transfer transitions. [12] However, a strong dipole-allowed transition exists in the Zener polaron (Section 13, Supporting Information). Initial and final state of the optical transition, denoted as (B) and (E) in Figure 7, are Mn 3d e g orbitals of σ-bond character, pointing toward the bridging oxygen ion.…”

Section: Jahn-teller Dimer Modelmentioning

confidence: 99%

“…Several manganites such as Pr 1-x Ca x MnO 3 , La 1-x Ca x MnO 3 (LCMO) and the semiconducting phase of La 1-x Sr x MnO 3 (LSMO) exhibit a strong small polaron IR optical absorption feature between 500 meV and 2 eV, [10][11][12][13] followed by chargetransfer (CT) transitions at higher energies. Figure 1a shows the optical conductivity.…”

Section: Introductionmentioning

confidence: 99%

“…[11,14,15] This absorption band at about 1.5 eV is generally attributed to a transition between Jahn-Teller (JT) split Mn 3d e g states (Figure 1b), either occurring as an intrasite or as an intersite transition between Mn 3+ and Mn 4+ sites. [12,16,17] The transition is broadened by a polaron hopping feature at 0.5-0.8 eV and coupling to a phonon bath. The JT effect describes the formation of polarons via strong electron-phonon coupling between an electron in a pair of degenerate electron states and nuclear distortions, i.e., phonons that lift the degeneracy by lowering the underlying symmetry.…”

Section: Introductionmentioning

confidence: 99%

“…[19] E 0 typically is of the order of 0.2-0.6 eV in manganites for x ≤ 0.5. [12,20] In a single JT active MnO 6 octahedron, an optical transition from the lower to the upper Mn 3d e g states at ΔE = 4 E 0 is dipole forbidden and can therefore not explain the observed dominant spectral absorption band in manganites. Similarly, radiative decay of the excited JT polaron is suppressed by the optical selection rules.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of Hot Polaron States with a Nanosecond Lifetime in a Manganite Perovskite

Raiser

Mildner

Ifland

et al. 2017

Advanced Energy Materials

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Understanding and controlling the relaxation process of optically excited charge carriers in solids with strong correlations is of great interest in the quest for new strategies to exploit solar energy. Usually, optically excited electrons in a solid thermalize rapidly on a femtosecond to picosecond timescale due to interactions with other electrons and phonons. New mechanisms to slow down thermalization will thus be of great significance for efficient light energy conversion, e.g., in photovoltaic devices. Ultrafast optical pump–probe experiments in the manganite Pr0.65Ca0.35MnO3, a photovoltaic, thermoelectric, and electrocatalytic material with strong polaronic correlations, reveal an ultraslow recombination dynamics on a nanosecond‐time scale. The nature of long living excitations is further elucidated by photovoltaic measurements, showing the presence of photodiffusion of excited electron–hole polaron pairs. Theoretical considerations suggest that the excited charge carriers are trapped in a hot polaron state. Escape from this state is possible via a slow dipole‐forbidden recombination process or via rare thermal fluctuations toward a conical intersection followed by a radiation‐less decay. The strong correlation between the excited polaron and the octahedral dynamics of its environment appears to be substantial for stabilizing the hot polaron.

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Rotating Ring–Disk Electrode Study of Oxygen Evolution at a Perovskite Surface: Correlating Activity to Manganese Concentration

Scholz

Risch

Stoerzinger³

et al. 2016

J. Phys. Chem. C

102

157

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Transition-metal oxides with the perovskite structure are promising catalysts to promote the kinetics of the oxygen evolution reaction (OER). To improve the activity and stability of these catalysts, a deeper understanding about the active site, the underlying reaction mechanism, and possible side reactions is necessary. We chose smooth epitaxial (100)-oriented La 0.6 Sr 0.4 MnO 3 (LSMO) films grown on Nb:SrTiO 3 (STNO) as a model electrode to investigate OER activity and stability using the rotating ring−disk electrode (RRDE) method. Careful electrochemical characterization of various films in the thickness range between 10 and 200 nm yields an OER activity of the epitaxial LSMO surface of 100 μA/cm 2 ox at 1.65 V vs RHE, which is among the highest reported for LSMO and close to (110)-oriented IrO 2 . Detailed post-mortem analysis using XPS, XRD, and AFM revealed the high structural and morphological stability of LSMO after OER. The observed correlation between activity and Mn vacancies on the surface suggested Mn as the active site for the OER in (100)-oriented LSMO, in contrast to similar perovskite manganites, such as Pr 1−x Ca x MnO 3 . The observed Tafel slope of about 60 mV/dec matches the theoretical prediction for a chemical ratelimiting step that follows an electrochemical pre-equilibrium, probably O−O bond formation. Our study established LSMO as an atomically flat oxide with high intrinsic activity and high stability.

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Publisher's Note: Temperature- and doping-dependent optical absorption in the small-polaron system Pr1−xCaxMnO3 [Phys. Rev. B 92 , 035145 (2015)]

Cited by 9 publications

References 0 publications

Electronic structure of Pr1−xCaxMnO3

Electronic structure of Pr1−xCaxMnO3

Evolution of Hot Polaron States with a Nanosecond Lifetime in a Manganite Perovskite

Rotating Ring–Disk Electrode Study of Oxygen Evolution at a Perovskite Surface: Correlating Activity to Manganese Concentration

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