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Kannan, K.; Arunarkavalli, T.; Rao, C. N. R.

doi:10.1103/physrevb.49.724

Cited by 64 publications

(45 citation statements)

References 12 publications

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“…The basis for the wide range of applications is related to the incorporation of various metal cations into the lattice of the parent magnetite structure. MnFe 2 O 4 is one of the most important magnetic materials which have been widely used in electronic applications [7,8] and contrast enhancement agents in magnetic resonance imaging (MRI) technology [9][10][11] in addition to recording media [12].…”

Section: Introductionmentioning

confidence: 99%

Effect of Sn–Ni substitution on the structural, electrical and magnetic properties of mixed spinel ferrites

Ashiq

Bibi

Malana

2010

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 99%

Effect of Sn–Ni substitution on the structural, electrical and magnetic properties of mixed spinel ferrites

Ashiq

Bibi

Malana

2010

Journal of Alloys and Compounds

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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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“…Manganese ferrite (MnFe 2 O 4 ) as a superparamagnetic nanoparticle has a very high magnetization capacity owing to its large magnetic spin magnitude [8]. It has been widely used in electronic [9,10], contrast-enhancement agents in MRI technology [11][12][13] and recording media [14]. However, magnetic properties of the nanoparticles and its application are strongly dependent on the size, shape, morphology and crystallinity of the nanoparticles [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%