Two-magnon processes and ferrimagnetic linewidth calculation in manganese ferrite

Flores, A. G.; Raposo, V.; Torres, L.; Íñiguez, J.

doi:10.1103/physrevb.59.9447

Cited by 15 publications

(13 citation statements)

References 36 publications

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“…The most typical crystal structures that exhibit three-dimensional geometric and magnetic frustration are spinels and pyrochlores. For several pyrochlores and spinels (R 2 Mo 2 O 7 [3]: R ¼ Sm, Gd and Tb, R 2 Nb 2 O 7 : R ¼ Sm, Gd, Tb, Dy, Ho, Er, Yb, Lu and Y, Tb 2 Ti 2 O 7 [4], MgAl 2 O 4 [5], NiAl 2 O 4 [6], NiFe 2 O 4 [7], MnFe 2 O 4 [8]), single crystals have been obtained by the float-zone (FZ) method. The FZ method has been known as one of the typical single crystal growth method for oxides with relatively high melting temperature.…”

Section: Introductionmentioning

confidence: 99%

Crystal growth of Germanium-based oxide spinels by the Float Zone Method

Hara

Yoshida

Ikeda

et al. 2005

Journal of Crystal Growth

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Section: Introductionmentioning

confidence: 99%

Crystal growth of Germanium-based oxide spinels by the Float Zone Method

Hara

Yoshida

Ikeda

et al. 2005

Journal of Crystal Growth

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“…This disorder has caused some confusion both in the analysis of the dependence of magnetic properties on sample size [4][5][6][7] and in understanding the temperature dependence of transport quantities. 12 There, we found that the electronic structure is highly sensitive to the structural parameters used, particularly, the internal O coordinate u of the spinel structure.…”

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confidence: 99%

Magnetism and electronic structure in ZnFe2O4 and MnFe2O4

Singh

Gupta

2002

Journal of Applied Physics

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Density functional calculations are used to study magnetic and electronic properties of the spinel ferrites, ZnFe2O4 and MnFe2O4. Correct magnetic orderings are obtained. ZnFe2O4 is predicted to be a small gap insulator in agreement with experiment. MnFe2O4 is found to be a low carrier density half-metal in the fully ordered state. However, strong effects on the electronic structure are found upon partial interchange of Fe and Mn atoms. This indicates that the insulating character may be due to Anderson localization associated with the intersite Mn-Fe disorder.Spinel structure ferrites play an important role in technologies because a large subset of these materials are room temperature, insulating ferromagnets. While the basic physics underlying the magnetic orderings has be understood since the work of Goodenough and coworkers, 12 There, we found that the electronic structure is highly sensitive to the structural parameters used, particularly, the internal O coordinate u of the spinel structure. For ZnFe 2 O 4 we used the experimental value determined from structural refinements. MnFe 2 O 4 has not been made in non-inverted form, so we instead used total energy minimization. In this way we obtained u=0.381 and a=8.49Å. With these and no inversion, we find the ferrimagnetic state to be the ground state. Specifically, we did total energy calculations for the ferrimagnetic state, a ferromagnetic state and antiferromagnetic A and B sublattices. The ferrimagnetic configuration was lowest in energy, e.g. by 2.03 eV per cell (2 Mn and 4 Fe ions) relative to the ferromagnetic. Details will be given in a longer report. 13In an ionic model, Fe has a trivalent high spin d 5 configuration, while both Zn and Mn are divalent, so Mn is also d 5 . We find a spin magnetization of exactly 10 µ B per unit cell in the ferrimagnetic state, as in the ionic model. As seen in the band structure (Fig. 1), this is due to a half-metallic state. The density of states (DOS) and projections (Fig. 2) show that the ionic model is followed, though there is some reduction in moments due to hybridization. There is a majority spin gap but only a pseudogap in the minority channel. The majority channel is described by the ionic model. It has O 2p bands from ∼ -8 eV (relative to the Fermi energy, E F ) to ∼ -3 eV. Fe t 2g bands overlap the top of these and extend to -2.3 eV. These are separated by a clean crystal field gap from an Fe e g manifold, which goes from -1.5 to -0.2 eV. The unoccupied Mn d bands are above +2 eV and show a smaller tetrahedral crystal field with overlapping e g and t 2g manifolds. As mentioned, the minority spin channel is metallic. This is a result of a manifold of 22 bands lying between -2 eV and 1 eV (Fig. 3). The lower part of this manifold (from -2 to -1 eV) is from 4 Mn e g bands, which are below the t 2g bands in the Mn tetrahedral crystal field. The next set (of 6), extending to E F , is Mn t 2g derived, while the remaining 12 bands are from 1

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“…Kasuya-Le Craw and rapidly relaxing impurities processes have also been omitted. 11 The expression for surface pit contribution is given as 10…”

Section: Methodsmentioning

confidence: 99%

Ferromagnetic resonance and electric characterization in double perovskite Sr2FeMoO6

Flores

Zazo

Raposo

et al. 2003

Journal of Applied Physics

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In this work the study of the ferromagnetic resonance (FMR) and of the electrical conductivity in the perovskite sample, Sr2FeMoO6, is presented. The sample has been manufactured by conventional ceramic method sintering in inert gas atmosphere. Electrical conductivity, of about 1000–1200 S/m, has been measured in the 125–300 K temperature range. FMR linewidths have been measured at 9.48 GHz from 125 to 300 K. A decrease of the linewidth with increasing temperature has been obtained. This behavior has been attributed to the presence of valence exchange mechanism, which takes places in samples with Fe2+ cations. In this way, FMR linewidth analysis has been revealed like a useful and clear technique in determining the cation distribution of the sample showing the presence of Fe2+ ions. This technique has also shown data about the microstructure of the sintered polycrystalline sample finding the porosity value of the sample.

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Two-magnon processes and ferrimagnetic linewidth calculation in manganese ferrite

Cited by 15 publications

References 36 publications

Crystal growth of Germanium-based oxide spinels by the Float Zone Method

Crystal growth of Germanium-based oxide spinels by the Float Zone Method

Magnetism and electronic structure in ZnFe2O4 and MnFe2O4

Ferromagnetic resonance and electric characterization in double perovskite Sr2FeMoO6

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