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Johan Lindén - One of the best experts on this subject based on the ideXlab platform.

  • eubafe2o5 weubafe2o5 w valence mixing and charge ordering are two separate Cooperative Phenomena
    Journal of Solid State Chemistry, 2007
    Co-Authors: Pavel Karen, K. Gustafsson, Johan Lindén
    Abstract:

    Mixed-valence EuBaFe2O5+wEuBaFe2O5+w exhibits a robust Verwey-type transition. The trend in the volume change suggests a first-order transition up to the nonstoichiometry level of about w=0.25w=0.25. 57Fe Mossbauer spectroscopy, differential scanning calorimetry and synchrotron X-ray powder diffraction are used to study the valence mixing and charge ordering in EuBaFe2O5+wEuBaFe2O5+w as a function of the nonstoichiometry parameter w. 151Eu Mossbauer spectroscopy is used as a selective probe into the ferromagnetic valence-mixing coupling along c above the Verwey transition, and reveals that increasing w destroys this coupling in favor of a G-type magnetic order in parallel with the progressive removal of the valence-mixed iron states accounted for by 57Fe Mossbauer spectroscopy. This removal proceeds according to a probability scheme of mixing between ferromagnetically coupled divalent and trivalent neighbor iron atoms along c across the R layer. In contrast, the concentration decrease of the orbital- and charge-ordered states in EuBaFe2O5+wEuBaFe2O5+w is found to be a linear function of w. Valence mixing and charge ordering are therefore two separate Cooperative Phenomena. The enthalpy of the Verwey-type transition between these two Cooperative systems is a linear function of w  , which suggests that it originates from the latent heat of freezing into the long-range ordered orbital- and charge-ordered state. The enthalpy becomes zero at the nonstoichiometry level of about w=0.25w=0.25.

  • eubafe2o5 w valence mixing and charge ordering are two separate Cooperative Phenomena
    Journal of Solid State Chemistry, 2007
    Co-Authors: Pavel Karen, K. Gustafsson, Johan Lindén
    Abstract:

    Abstract Mixed-valence EuBaFe 2 O 5 + w exhibits a robust Verwey-type transition. The trend in the volume change suggests a first-order transition up to the nonstoichiometry level of about w = 0.25 . 57Fe Mossbauer spectroscopy, differential scanning calorimetry and synchrotron X-ray powder diffraction are used to study the valence mixing and charge ordering in EuBaFe 2 O 5 + w as a function of the nonstoichiometry parameter w. 151Eu Mossbauer spectroscopy is used as a selective probe into the ferromagnetic valence-mixing coupling along c above the Verwey transition, and reveals that increasing w destroys this coupling in favor of a G-type magnetic order in parallel with the progressive removal of the valence-mixed iron states accounted for by 57Fe Mossbauer spectroscopy. This removal proceeds according to a probability scheme of mixing between ferromagnetically coupled divalent and trivalent neighbor iron atoms along c across the R layer. In contrast, the concentration decrease of the orbital- and charge-ordered states in EuBaFe 2 O 5 + w is found to be a linear function of w. Valence mixing and charge ordering are therefore two separate Cooperative Phenomena. The enthalpy of the Verwey-type transition between these two Cooperative systems is a linear function of w, which suggests that it originates from the latent heat of freezing into the long-range ordered orbital- and charge-ordered state. The enthalpy becomes zero at the nonstoichiometry level of about w = 0.25 .

  • EuBaFe2O5+w : Valence mixing and charge ordering are two separate Cooperative Phenomena
    Journal of Solid State Chemistry, 2006
    Co-Authors: Pavel Karen, K. Gustafsson, Johan Lindén
    Abstract:

    Abstract Mixed-valence EuBaFe 2 O 5 + w exhibits a robust Verwey-type transition. The trend in the volume change suggests a first-order transition up to the nonstoichiometry level of about w = 0.25 . 57Fe Mossbauer spectroscopy, differential scanning calorimetry and synchrotron X-ray powder diffraction are used to study the valence mixing and charge ordering in EuBaFe 2 O 5 + w as a function of the nonstoichiometry parameter w. 151Eu Mossbauer spectroscopy is used as a selective probe into the ferromagnetic valence-mixing coupling along c above the Verwey transition, and reveals that increasing w destroys this coupling in favor of a G-type magnetic order in parallel with the progressive removal of the valence-mixed iron states accounted for by 57Fe Mossbauer spectroscopy. This removal proceeds according to a probability scheme of mixing between ferromagnetically coupled divalent and trivalent neighbor iron atoms along c across the R layer. In contrast, the concentration decrease of the orbital- and charge-ordered states in EuBaFe 2 O 5 + w is found to be a linear function of w. Valence mixing and charge ordering are therefore two separate Cooperative Phenomena. The enthalpy of the Verwey-type transition between these two Cooperative systems is a linear function of w, which suggests that it originates from the latent heat of freezing into the long-range ordered orbital- and charge-ordered state. The enthalpy becomes zero at the nonstoichiometry level of about w = 0.25 .

Pavel Karen - One of the best experts on this subject based on the ideXlab platform.

  • eubafe2o5 weubafe2o5 w valence mixing and charge ordering are two separate Cooperative Phenomena
    Journal of Solid State Chemistry, 2007
    Co-Authors: Pavel Karen, K. Gustafsson, Johan Lindén
    Abstract:

    Mixed-valence EuBaFe2O5+wEuBaFe2O5+w exhibits a robust Verwey-type transition. The trend in the volume change suggests a first-order transition up to the nonstoichiometry level of about w=0.25w=0.25. 57Fe Mossbauer spectroscopy, differential scanning calorimetry and synchrotron X-ray powder diffraction are used to study the valence mixing and charge ordering in EuBaFe2O5+wEuBaFe2O5+w as a function of the nonstoichiometry parameter w. 151Eu Mossbauer spectroscopy is used as a selective probe into the ferromagnetic valence-mixing coupling along c above the Verwey transition, and reveals that increasing w destroys this coupling in favor of a G-type magnetic order in parallel with the progressive removal of the valence-mixed iron states accounted for by 57Fe Mossbauer spectroscopy. This removal proceeds according to a probability scheme of mixing between ferromagnetically coupled divalent and trivalent neighbor iron atoms along c across the R layer. In contrast, the concentration decrease of the orbital- and charge-ordered states in EuBaFe2O5+wEuBaFe2O5+w is found to be a linear function of w. Valence mixing and charge ordering are therefore two separate Cooperative Phenomena. The enthalpy of the Verwey-type transition between these two Cooperative systems is a linear function of w  , which suggests that it originates from the latent heat of freezing into the long-range ordered orbital- and charge-ordered state. The enthalpy becomes zero at the nonstoichiometry level of about w=0.25w=0.25.

  • eubafe2o5 w valence mixing and charge ordering are two separate Cooperative Phenomena
    Journal of Solid State Chemistry, 2007
    Co-Authors: Pavel Karen, K. Gustafsson, Johan Lindén
    Abstract:

    Abstract Mixed-valence EuBaFe 2 O 5 + w exhibits a robust Verwey-type transition. The trend in the volume change suggests a first-order transition up to the nonstoichiometry level of about w = 0.25 . 57Fe Mossbauer spectroscopy, differential scanning calorimetry and synchrotron X-ray powder diffraction are used to study the valence mixing and charge ordering in EuBaFe 2 O 5 + w as a function of the nonstoichiometry parameter w. 151Eu Mossbauer spectroscopy is used as a selective probe into the ferromagnetic valence-mixing coupling along c above the Verwey transition, and reveals that increasing w destroys this coupling in favor of a G-type magnetic order in parallel with the progressive removal of the valence-mixed iron states accounted for by 57Fe Mossbauer spectroscopy. This removal proceeds according to a probability scheme of mixing between ferromagnetically coupled divalent and trivalent neighbor iron atoms along c across the R layer. In contrast, the concentration decrease of the orbital- and charge-ordered states in EuBaFe 2 O 5 + w is found to be a linear function of w. Valence mixing and charge ordering are therefore two separate Cooperative Phenomena. The enthalpy of the Verwey-type transition between these two Cooperative systems is a linear function of w, which suggests that it originates from the latent heat of freezing into the long-range ordered orbital- and charge-ordered state. The enthalpy becomes zero at the nonstoichiometry level of about w = 0.25 .

  • EuBaFe2O5+w : Valence mixing and charge ordering are two separate Cooperative Phenomena
    Journal of Solid State Chemistry, 2006
    Co-Authors: Pavel Karen, K. Gustafsson, Johan Lindén
    Abstract:

    Abstract Mixed-valence EuBaFe 2 O 5 + w exhibits a robust Verwey-type transition. The trend in the volume change suggests a first-order transition up to the nonstoichiometry level of about w = 0.25 . 57Fe Mossbauer spectroscopy, differential scanning calorimetry and synchrotron X-ray powder diffraction are used to study the valence mixing and charge ordering in EuBaFe 2 O 5 + w as a function of the nonstoichiometry parameter w. 151Eu Mossbauer spectroscopy is used as a selective probe into the ferromagnetic valence-mixing coupling along c above the Verwey transition, and reveals that increasing w destroys this coupling in favor of a G-type magnetic order in parallel with the progressive removal of the valence-mixed iron states accounted for by 57Fe Mossbauer spectroscopy. This removal proceeds according to a probability scheme of mixing between ferromagnetically coupled divalent and trivalent neighbor iron atoms along c across the R layer. In contrast, the concentration decrease of the orbital- and charge-ordered states in EuBaFe 2 O 5 + w is found to be a linear function of w. Valence mixing and charge ordering are therefore two separate Cooperative Phenomena. The enthalpy of the Verwey-type transition between these two Cooperative systems is a linear function of w, which suggests that it originates from the latent heat of freezing into the long-range ordered orbital- and charge-ordered state. The enthalpy becomes zero at the nonstoichiometry level of about w = 0.25 .

K. Gustafsson - One of the best experts on this subject based on the ideXlab platform.

  • eubafe2o5 weubafe2o5 w valence mixing and charge ordering are two separate Cooperative Phenomena
    Journal of Solid State Chemistry, 2007
    Co-Authors: Pavel Karen, K. Gustafsson, Johan Lindén
    Abstract:

    Mixed-valence EuBaFe2O5+wEuBaFe2O5+w exhibits a robust Verwey-type transition. The trend in the volume change suggests a first-order transition up to the nonstoichiometry level of about w=0.25w=0.25. 57Fe Mossbauer spectroscopy, differential scanning calorimetry and synchrotron X-ray powder diffraction are used to study the valence mixing and charge ordering in EuBaFe2O5+wEuBaFe2O5+w as a function of the nonstoichiometry parameter w. 151Eu Mossbauer spectroscopy is used as a selective probe into the ferromagnetic valence-mixing coupling along c above the Verwey transition, and reveals that increasing w destroys this coupling in favor of a G-type magnetic order in parallel with the progressive removal of the valence-mixed iron states accounted for by 57Fe Mossbauer spectroscopy. This removal proceeds according to a probability scheme of mixing between ferromagnetically coupled divalent and trivalent neighbor iron atoms along c across the R layer. In contrast, the concentration decrease of the orbital- and charge-ordered states in EuBaFe2O5+wEuBaFe2O5+w is found to be a linear function of w. Valence mixing and charge ordering are therefore two separate Cooperative Phenomena. The enthalpy of the Verwey-type transition between these two Cooperative systems is a linear function of w  , which suggests that it originates from the latent heat of freezing into the long-range ordered orbital- and charge-ordered state. The enthalpy becomes zero at the nonstoichiometry level of about w=0.25w=0.25.

  • eubafe2o5 w valence mixing and charge ordering are two separate Cooperative Phenomena
    Journal of Solid State Chemistry, 2007
    Co-Authors: Pavel Karen, K. Gustafsson, Johan Lindén
    Abstract:

    Abstract Mixed-valence EuBaFe 2 O 5 + w exhibits a robust Verwey-type transition. The trend in the volume change suggests a first-order transition up to the nonstoichiometry level of about w = 0.25 . 57Fe Mossbauer spectroscopy, differential scanning calorimetry and synchrotron X-ray powder diffraction are used to study the valence mixing and charge ordering in EuBaFe 2 O 5 + w as a function of the nonstoichiometry parameter w. 151Eu Mossbauer spectroscopy is used as a selective probe into the ferromagnetic valence-mixing coupling along c above the Verwey transition, and reveals that increasing w destroys this coupling in favor of a G-type magnetic order in parallel with the progressive removal of the valence-mixed iron states accounted for by 57Fe Mossbauer spectroscopy. This removal proceeds according to a probability scheme of mixing between ferromagnetically coupled divalent and trivalent neighbor iron atoms along c across the R layer. In contrast, the concentration decrease of the orbital- and charge-ordered states in EuBaFe 2 O 5 + w is found to be a linear function of w. Valence mixing and charge ordering are therefore two separate Cooperative Phenomena. The enthalpy of the Verwey-type transition between these two Cooperative systems is a linear function of w, which suggests that it originates from the latent heat of freezing into the long-range ordered orbital- and charge-ordered state. The enthalpy becomes zero at the nonstoichiometry level of about w = 0.25 .

  • EuBaFe2O5+w : Valence mixing and charge ordering are two separate Cooperative Phenomena
    Journal of Solid State Chemistry, 2006
    Co-Authors: Pavel Karen, K. Gustafsson, Johan Lindén
    Abstract:

    Abstract Mixed-valence EuBaFe 2 O 5 + w exhibits a robust Verwey-type transition. The trend in the volume change suggests a first-order transition up to the nonstoichiometry level of about w = 0.25 . 57Fe Mossbauer spectroscopy, differential scanning calorimetry and synchrotron X-ray powder diffraction are used to study the valence mixing and charge ordering in EuBaFe 2 O 5 + w as a function of the nonstoichiometry parameter w. 151Eu Mossbauer spectroscopy is used as a selective probe into the ferromagnetic valence-mixing coupling along c above the Verwey transition, and reveals that increasing w destroys this coupling in favor of a G-type magnetic order in parallel with the progressive removal of the valence-mixed iron states accounted for by 57Fe Mossbauer spectroscopy. This removal proceeds according to a probability scheme of mixing between ferromagnetically coupled divalent and trivalent neighbor iron atoms along c across the R layer. In contrast, the concentration decrease of the orbital- and charge-ordered states in EuBaFe 2 O 5 + w is found to be a linear function of w. Valence mixing and charge ordering are therefore two separate Cooperative Phenomena. The enthalpy of the Verwey-type transition between these two Cooperative systems is a linear function of w, which suggests that it originates from the latent heat of freezing into the long-range ordered orbital- and charge-ordered state. The enthalpy becomes zero at the nonstoichiometry level of about w = 0.25 .

Keiichiro Nasu - One of the best experts on this subject based on the ideXlab platform.

  • Model of transient Cooperative Phenomena triggered by THz-pulse irradiation
    Journal of Physics: Conference Series, 2015
    Co-Authors: Kunio Ishida, Keiichiro Nasu
    Abstract:

    We studied the Cooperative Phenomena induced by injection of coherent phonons by THz optical pulses. Based on the analogy to the photoinduced phase transitions observed in various materials, we consider that Cooperative interactions between electrons and coherent phonons will lead to the multiplication of excited electrons and/or growth of a transient phase, which is understood by bifurcation of quantum-mechanical wavepackets on adiabatic potential energy surfaces. Employing a model of localized electrons coupled with a quantized optical phonon mode, we discuss the dynamics of the Cooperative Phenomena by THz-pulse irradiation and, in particular, the role of the number and/or the initial distribution of phonons in the initial creation process of transient phases.

  • Numerical simulation on the dynamics of photoinduced Cooperative Phenomena in molecular crystals
    Computer Physics Communications, 2009
    Co-Authors: Kunio Ishida, Keiichiro Nasu
    Abstract:

    We develop a new simulation method to study the dynamics of initial nucleation processes of photoinduced structural change of molecular crystals. In order to describe the nonadiabatic transition in each molecule, we employ a model of localized electrons coupled with a fully quantized phonon mode, and the time-dependent Schrodinger equation for the model is numerically solved. By applying a mean-field approximation in solving the Schrodinger equation, the calculation method is quite efficient on parallel computing systems. We show that coherently driven molecular distortion plays an important role in the successive conversion of electronic states which leads to photoinduced Cooperative Phenomena.

  • Multifractal analysis of photoinduced Cooperative Phenomena
    Journal of Physics: Condensed Matter, 2007
    Co-Authors: Kunio Ishida, Keiichiro Nasu
    Abstract:

    We study the multifractal properties of the geometrical patterns which appear in the initial processes of photoinduced structural change. Employing a model of localized electrons coupled with a single-phonon mode, we calculate the Lipschitz–Holder exponent α and singularity spectrum f(α) on the distribution of excited electronic states and molecular distortion by using the box-counting method, and discuss the temporal behavior of photoinduced domains.

Kunio Ishida - One of the best experts on this subject based on the ideXlab platform.

  • Model of transient Cooperative Phenomena triggered by THz-pulse irradiation
    Journal of Physics: Conference Series, 2015
    Co-Authors: Kunio Ishida, Keiichiro Nasu
    Abstract:

    We studied the Cooperative Phenomena induced by injection of coherent phonons by THz optical pulses. Based on the analogy to the photoinduced phase transitions observed in various materials, we consider that Cooperative interactions between electrons and coherent phonons will lead to the multiplication of excited electrons and/or growth of a transient phase, which is understood by bifurcation of quantum-mechanical wavepackets on adiabatic potential energy surfaces. Employing a model of localized electrons coupled with a quantized optical phonon mode, we discuss the dynamics of the Cooperative Phenomena by THz-pulse irradiation and, in particular, the role of the number and/or the initial distribution of phonons in the initial creation process of transient phases.

  • Numerical simulation on the dynamics of photoinduced Cooperative Phenomena in molecular crystals
    Computer Physics Communications, 2009
    Co-Authors: Kunio Ishida, Keiichiro Nasu
    Abstract:

    We develop a new simulation method to study the dynamics of initial nucleation processes of photoinduced structural change of molecular crystals. In order to describe the nonadiabatic transition in each molecule, we employ a model of localized electrons coupled with a fully quantized phonon mode, and the time-dependent Schrodinger equation for the model is numerically solved. By applying a mean-field approximation in solving the Schrodinger equation, the calculation method is quite efficient on parallel computing systems. We show that coherently driven molecular distortion plays an important role in the successive conversion of electronic states which leads to photoinduced Cooperative Phenomena.

  • Multifractal analysis of photoinduced Cooperative Phenomena
    Journal of Physics: Condensed Matter, 2007
    Co-Authors: Kunio Ishida, Keiichiro Nasu
    Abstract:

    We study the multifractal properties of the geometrical patterns which appear in the initial processes of photoinduced structural change. Employing a model of localized electrons coupled with a single-phonon mode, we calculate the Lipschitz–Holder exponent α and singularity spectrum f(α) on the distribution of excited electronic states and molecular distortion by using the box-counting method, and discuss the temporal behavior of photoinduced domains.