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Zaag, PJ van der; Brabers, V.A.M.; Johnson, M.T.; Noordermeer, A.; Bongers, P. F.

doi:10.1103/physrevb.51.12009

Cited by 65 publications

(30 citation statements)

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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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confidence: 99%

Magnetism and electronic structure in ZnFe2O4 and MnFe2O4

Singh

Gupta

2002

Journal of Applied Physics

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“…11 However, the strength of exchange interaction for Mn 2+ (A)-Fe 3+ (B) is smaller than that of Fe 3+ (A)-Fe 3+ (B). 5,6,12,13 Hence any change in inversion affects the exchange constant but not the net magnetic moment. 6,11,12 In this paper, we report the magnetic properties of MnFe 2 O 4 thin films pulsed laser deposited (PLD) at various substrate temperatures (T S ).…”

Section: Introductionmentioning

confidence: 99%

“…5,6,12,13 Hence any change in inversion affects the exchange constant but not the net magnetic moment. 6,11,12 In this paper, we report the magnetic properties of MnFe 2 O 4 thin films pulsed laser deposited (PLD) at various substrate temperatures (T S ). We have estimated the value of exchange stiffness constant (D) by fitting the temperature dependence of magnetization data to Bloch's law and determined the effect of deposition temperature on the values of D in thin films and hence on the inversion of these films.…”

Section: Introductionmentioning

confidence: 99%

Effect of substrate temperature on magnetic properties of MnFe2O4 thin films

et al. 2017

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MnFe2O4 thin films were pulsed laser deposited on to quartz substrate from room temperature (RT) to 650 °C in a pure argon environment. Temperature dependence of spontaneous magnetization (4πMS) was measured on these films from 10 K to 350 K using a vibrating sample magnetometer. Ferromagnetic resonance (FMR) study was also carried out at 300 K. The exchange stiffness constant (D) values were obtained by fitting the 4πMS data to the Bloch’s equation. The D values of the films thus found decreases while the 4πMS value increases, though non-monotonically, with the increase in TS and tend to reach bulk values at TS = 650 °C. The variation in D and 4πMS values of the films are explained based on the degree of inversion and oxidation state of cations in thin films.

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“…to Mn 3? and different cation distributions of ferrite nanoparticles can decrease the lattice constant [31,32]. Density of the prepared samples was calculated using the Archimedes principle from precise measurements of the dry, saturated and suspended weight.…”

Section: Xrd Analysismentioning

confidence: 99%

MnCrxFe2−xO4 Nanoparticles: Magnetic and Microwave Absorption Properties

Baykal

Genç

Elmal

et al. 2015

J Inorg Organomet Polym

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Chromium substituted Mn nanospinel ferrites having the formula MnCr x Fe 2-x O 4 (0.0 B x B 1.0) have been synthesized using the microwave-assisted combustion synthesis. The composition, structural, spectroscopic features of the products were studied by X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. XRD investigations indicated the formation of single-phased cubic spinel structure for all products. Lattice parameters of the products represented the continuous decrease with increasing the substitution of Cr 3? . The saturation magnetization of undoped sample appeared to be highest and as Cr 3? concentration increases magnetization of the samples decreases. There is one reflection loss minimum in all doped samples at around 13 GHz with magnitude of -12 dB mechanism of which is explained by quarter wave cancellation model.

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Comment on ‘‘Particle-size effects on the value ofTCofMnFe2

Cited by 65 publications

References 13 publications

Magnetism and electronic structure in ZnFe2O4 and MnFe2O4

Magnetism and electronic structure in ZnFe2O4 and MnFe2O4

Effect of substrate temperature on magnetic properties of MnFe2O4 thin films

MnCrxFe2−xO4 Nanoparticles: Magnetic and Microwave Absorption Properties

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