Infra-red reflectivity of non-stoichiometric ferrous Oxide

Prevot, B.; Biellmann, J.; Meftah, Mahdi; Sieskind, M.

doi:10.1002/pssa.2210400217

Cited by 14 publications

(8 citation statements)

References 21 publications

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“…Infrared reflectivity experiments on ferrous oxide with the main focus on phonon properties and conductivity contributions of free charge carriers at elevated temperatures have been performed by Bowen et al [24], Prevot et al [51] and by Henning and Mutschke [52]. Recently, Seagle et al [53] have investigated the phonon properties and conductivity contributions of Fe 0.91 O as function of hydrostatic pressure.…”

Section: Optical Propertiesmentioning

confidence: 99%

Wüstite: electric, thermodynamic and optical properties of FeO

et al. 2012

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Abstract. We report on a systematic optical investigation of wüstite. In addition, the sample under consideration, Fe0.93O, has been characterized in detail by electrical transport, dielectric, magnetic and thermodynamic measurements. From infrared reflectivity experiments, phonon properties, Drude-like conductivity contributions and electronic transitions have been systematically investigated. The phonon modes reveal a clear splitting below the antiferromagnetic ordering temperature, similar to observations in other transitionmetal monoxides and in spinel compounds which have been explained in terms of a spin-driven Jahn-Teller effect. The electronic transitions can best be described assuming a crystal-field parameter Dq = 750 cm −1 and a spin-orbit coupling constant λ = 95 cm −1 . A well defined crystal field excitation at low temperatures reveals significant broadening on increasing temperature with an overall transfer of optical weight into dc conductivity contributions. This fact seems to indicate a melting of the on-site excitation into a Drude behavior of delocalized charge carriers. The optical band gap in wüstite is close to 1.0 eV at room temperature. With decreasing temperatures and passing the magnetic phase transition we have detected a strong blue shift of the correlation-induced band edge, which amounts more than 15% and has been rarely observed in antiferromagnets.

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Section: Optical Propertiesmentioning

confidence: 99%

Wüstite: electric, thermodynamic and optical properties of FeO

et al. 2012

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“…Recently, some of the authors have reported on the temperature dependence, having identified three distinct oscillators at 5 K [38]. FeO was investigated by means of optical spectroscopy in the FIR domain first by Bowen et al [39] and Prévot et al [40]. Spectra recorded at various temperatures are also provided in [41] and recently a pressure dependent study up to 33 GPa has been performed [42].…”

Section: Mnomentioning

confidence: 99%

“…as proposed in literature [40,42]. The second term on the right hand side represents a Drude like contribution and accounts for free charge carriers with plasma frequency Ω P and damping γ P , while each addend of the sum describes one normal mode according to a Lorentz oscillator.…”

Section: Feomentioning

confidence: 99%

Spin-phonon coupling in highly correlated transition-metal monoxides

Kant

Mayr

Rudolf

et al. 2009

Eur. Phys. J. Spec. Top.

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We report on the optical response of the highly correlated transitionmetal monoxides MnO, FeO, CoO and NiO in the far-infrared regime. The main focus is put on spin-phonon coupling effects, which are found to significantly influence the lattice dynamics in the magnetically ordered phase. Measurements have been performed in the ordered and paramagnetic state for temperatures up to 550 K. A clear splitting of the cubic mode accompanying the transition into long range magnetic order can be identified in MnO, CoO and NiO. In the case of FeO it is argued that an anisotropic phonon response seems to be very likely, though it could not be observed directly. The results are compared to recent experimental and theoretical studies in frustrated magnets, which predict the splitting of zone center phonon modes induced by a non-cubic spin-density distribution.

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“…The point defects as well as their clusters are likely to affect the dielectric and optical properties of FeO. The results of various experiments [16][17][18][19][20][21][22][23][24] indicate some peculiar behavior of the measured optical quantities in wüstite and assign it to the native defects. However, a detailed explanation of the influence of such defects on the electronic and dielectric properties of FeO remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Influence of isolated and clustered defects on electronic and dielectric properties of wüstite

et al. 2015

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The influence of intrinsic Fe defects in FeO (either single cation vacancies or prototypical 4:1 vacancy clusters) on the electronic and dielectric properties is studied within the density functional theory. The importance of local Coulomb interactions at Fe atoms is highlighted and shown to be responsible for the observed insulating Mott gap in FeO which is reduced by the presence of defects. We investigate nonstoichiometric configurations of Fe1−xO with x ranging from 3 to 9% and find the aliovalent Fe cations in both the regular and interstitial lattice sites of the considered configurations. Furthermore, we show that the trivalent Fe ions are induced by both isolated and clustered Fe-vacancies and introduce the empty band states inside the insulating gap, which decreases monotonically with increasing cation vacancy concentration. The Fe1−xO systems with high defect content become metallic for small values of the Coulomb interaction U , yielding the increase in the dielectric functions and optical reflectivity at low energies in agreement with the experimental data. Due to the crystal defects, the infrared-active transverse optic phonons split and distribute over a wide range of frequencies clarifying the origin of the exceptionally large spectral linewidths of the dielectric loss functions observed for wüstite in recent experiments.

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Infra-red reflectivity of non-stoichiometric ferrous Oxide

Cited by 14 publications

References 21 publications

Wüstite: electric, thermodynamic and optical properties of FeO

Wüstite: electric, thermodynamic and optical properties of FeO

Spin-phonon coupling in highly correlated transition-metal monoxides

Influence of isolated and clustered defects on electronic and dielectric properties of wüstite

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