Mössbauer Effect in MgO:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Fe</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>2</mml:mn><mml:mn /></mml:mrow></mml:msup></mml:mrow></mml:math>; Low-Temperature Quadrupole Splitting

Leider, H.R.; Pipkorn, D.N.

doi:10.1103/physrev.165.494

Cited by 74 publications

(9 citation statements)

References 30 publications

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“…The reason might be more favorable annealing conditions (lower defect migration energies). The QS for Fe S is surprising when Fe substitutes Mg in a cubic structure but was also seen in a former publication [13], [9]. It is seen in this analysis that the data overlap quite well with EPR data showing that the relaxation in zero field (MS) and with applied magnetic field (EPR) is comparable and hence, that T 1 can be used as fluctuation time τ C for describing line broadening (relaxation) in MS.…”

Section: Mgosupporting

confidence: 69%

Magnetism in iron implanted oxides: a status report

et al. 2010

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Emission Mössbauer spectroscopy on 57 Fe fed by 57 Mn ions implanted in the metal oxides ZnO, MgO and Al 2 O 3 has been performed. The implanted ions occupy different lattice sites and charge states. A magnetic part of the spectra in each oxide can be assigned to Fe 3+ ions in a paramagnetic state with unusually long relaxation time observable to temperatures up to several hundreds Kelvin. Earlier expectations that the magnetic spectra could correspond to an ordered magnetic state could not be confirmed. A clear decision for paramagnetism and against an ordered magnetic state was achieved by applying a strong magnetic field of 0.6 Tesla.The relaxation times deduced were compared to spin-lattice relaxation times from electron paramagnetic resonance (EPR).

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Section: Mgosupporting

confidence: 69%

Magnetism in iron implanted oxides: a status report

et al. 2010

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“…It is only very recently that one realizes that this transition may involve not only charge ordering of Fe 2+ and Fe 3+ ions but also t 2g orbital ordering at the Fe 2+ sites. [3][4][5] Important in this regard are the recent results from band theory studies 6,7 in which the charge and orbital occupations were calculated based on the available crystal structure data. 3,4 It is highly desired to determine experimentally the electronic structure of Fe 3 O 4 and especially the local energetics of the Fe 2+ sites in order to test the conditions under which the t 2g orbital polarization and ordering can occur.…”

mentioning

confidence: 99%

“…We thus find no indication for the presence of Fe 3+ or Fe 1+ ions in our MBE-grown thin film samples, in contrast to other earlier studies. 23,24,[26][27][28][29] Continuing now with the D 4h scenario, we also have simulated the temperature dependence of the Fe L 3 and L 2 XAS spectra. Fig.…”

mentioning

confidence: 99%

“…On the other hand, the measurement by Goering et al 37 of 0.01 µ B would support the scenario for real space orbitals and large static Jahn-Teller distortions, much more in line with the recent theoretical studies. 6,7 Nevertheless, the issue on the magnitude of the orbital moment is not clear and is subject of debate. 38,39 To conclude, we have succeeded in preparing the Fe 2+ :MgO impurity system using MBE thin film technology.…”

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confidence: 99%

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Local electronic structure ofFe2+impurities in MgO thin films: Temperature-dependent soft x-ray absorption spectroscopy study

Haupricht¹,

Sutarto²,

Haverkort³

et al. 2010

Phys. Rev. B

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We report on the local electronic structure of Fe impurities in MgO thin films. Using soft x-ray absorption spectroscopy (XAS) we verified that the Fe impurities are all in the 2+ valence state. The fine details in the line shape of the Fe L2,3 edges provide direct evidence for the presence of a dynamical Jahn-Teller distortion. We are able to determine the magnitude of the effective D 4h crystal field energies. We also observed a strong temperature dependence in the spectra which we can attribute to the thermal population of low-lying excited states that are present due to the spin-orbit coupling in the Fe 3d. Using this Fe 2+ impurity system as an example, we show that an accurate measurement of the orbital moment in Fe3O4 will provide a direct estimate for the effective local low-symmetry crystal fields on the Fe 2+ sites, important for the theoretical modeling of the formation of orbital ordering.PACS numbers: 71.70. Ch, 71.70.Ej, 75.10.Dg, 78.70.Dm Magnetite is one of the most controversially discussed systems in solid state physics.1 It shows a first order anomaly in the temperature dependence of the electrical conductivity at 120 K, i.e., the famous Verwey transition 2 which is accompanied by a structural phase transition from the cubic inverse spinel to a distorted structure. It is only very recently that one realizes that this transition may involve not only charge ordering of Fe 2+and Fe 3+ ions but also t 2g orbital ordering at the Fe 2+sites.3-5 Important in this regard are the recent results from band theory studies 6,7 in which the charge and orbital occupations were calculated based on the available crystal structure data. 3,4It is highly desired to determine experimentally the electronic structure of Fe 3 O 4 and especially the local energetics of the Fe 2+ sites in order to test the conditions under which the t 2g orbital polarization and ordering can occur. Unfortunately, a direct approach to this system is difficult since the simultaneous presence of Fe 2+ and Fe 3+ valences as well as octahedral and tetrahedral sites makes standard electron spectroscopic methods to yield rather broad spectral line shapes, i.e., too featureless for a precise analysis concerning the details about the effective crystal fields with a symmetry lower than O h . 8Here we report on our study of the electronic structure of Fe impurities in MgO thin films. Having the local quasi-octahedral (O h ) symmetry and similar metaloxygen bond lengths, the impurity system could serve as a valuable reference for the more complex Fe 2+ containing magnetite. Using soft x-ray absorption spectroscopy (XAS) and an analysis based on full multiplet cluster calculations we found that the Fe impurities are all in the 2+ charge state and that a dynamical Jahn-Teller distortion is clearly present. The spectra showed a strong temperature dependence which can be traced back to the existence of low-lying excited states due to the presence of the spin-orbit interaction. We were able to make estimates concerning the magnitude and temperature ...

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“…2) In MgO, where the substitutional Fe2+ impurities occupy dctahedral sites, the 5T2-r5g level is now the ground level and it can be easily studied by MAS. Now such a study, made in 1968 by Leider and Pipkom [17], showed that the corresponding absorption line just splits below 14 K, with a separation value QS (r5g) = 0.33 mm/s.…”

Section: (B) Contribution Emitted By Non Cubic Site Fe2 + Ionsmentioning

confidence: 97%

Mössbauer absorption and emission experiments in CaF2(57Fe): relaxation and after-effect study

Garcin¹,

Imbert²,

Jéhanno³

et al. 1986

J. Phys. France

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La totalité du spectre d'absorption Mössbauer d'impuretés de 57Fe dans CaF2 et la plus grande partie du spectre Mössbauer émis par une source de 57Co dans CaF2 (échantillon en poudre) proviennent d'ions Fe2+ substitués en site cubique. Une faible contribution provenant de l'état de charge Fe1+ (3d7) est également détectée dans les spectres d'émission, mais on n'y observe pas de contribution de type Fe3+. Le spectre émis par les ions Fe2 + en site cubique comporte à basse température deux contributions issues de niveaux électroniques excités, à long temps de vie, et peuplés hors équilibre thermique. La première de celles-ci émane du triplet de spin-orbit 5E-03934 de faible énergie (E ~ 16 cm-1), dont les propriétés de relaxation ont été analysées d'autre part en spectrométrie d'absorption. La seconde émane probablement du niveau excité 5T2 -03935g de grande énergie (E ~ 5 000 cm-1).Abstract. -The entire Mössbauer absorption spectrum of 57Fe impurities in CaF2 and the main part of the emission spectrum of a CaF2 (57Co) powder sample originate from substitutional Fe2+ ions in cubic sites. A weak Fe1+ (3d7) charge state contribution is also detected in the emission spectra, but no Fe3+ contribution is observed. Two long-lived excited electronic level contributions are evidenced out of the thermal equilibrium in the low temperature emission spectra of the cubic site Fe2+ ions. The first originates from the low energy spin-orbit triplet 5E -03934 (E ~ 16 cm-1), whose relaxation properties are also analysed by absorption spectroscopy, and the second probably originates from the highly excited level 5T2 -03935g (E ~ 5 000 cm-1).

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Mössbauer Effect in MgO:Fe+2; Low-Temperature Quadrupole Splitting

Cited by 74 publications

References 30 publications

Magnetism in iron implanted oxides: a status report

Magnetism in iron implanted oxides: a status report

Local electronic structure ofFe2+impurities in MgO thin films: Temperature-dependent soft x-ray absorption spectroscopy study

Mössbauer absorption and emission experiments in CaF2(57Fe): relaxation and after-effect study

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