Evidence from infrared spectra for the magnetic moment directions of CR cations in the spinel ferrites

Tang, Gongguo; Shang, Z.F.; Zhang, X.Y.; Xu, Jie; Li, Z.Z.; Zhen, Congmian; Qi, Wu; Lang, Lili

doi:10.1016/j.physb.2015.01.035

Cited by 24 publications

(10 citation statements)

References 34 publications

(39 reference statements)

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“…It can be seen that for all samples the residual factor is R p ≤4.53, the weight residual factor is R wp ≤5.69 and the goodness-of-fit factor is s≤1. 43. These parameters confirm that the refinements are acceptable and that the sample compositions are the same as their nominal compositions, including that the oxygen content was 3 for all the samples.…”

Section: Results and Analysissupporting

confidence: 68%

“…Taking into account the requirement that a portion of the O ions be O 1-anions, our group investigated the magnetic structure and cation distributions for several series of spinel ferrites [34][35][36][37][38][39][40][41][42][43] using a quantum mechanical potential barrier model, in which the second and third ionization energies of the cations were used to calculate the probabilities presented different cations. 44 In the process of these research, we also developed an O2p itinerant electron model, 34 and found that using these models to replace the SE and DE models, the magnetic structures of not only Co, Ni, Cu doped spinel ferrites could be explained, but also those of the Cr, [36][37][38][39]42 Mn 34,40 and Ti 41 doped spinel ferrites, for which there have been many ongoing disputes regarding the cation distributions.…”

Section: O2p Itinerant Electron Modelmentioning

confidence: 99%

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Study of magnetic ordering in the perovskite manganites Pr0.6Sr0.4CrxMn1-xO3

et al. 2017

AIP Advances

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Powder samples of the ABO3 perovskite manganites Pr0.6Sr0.4CrxMn1-xO3 (0.00≤x≤0.30) were synthesized using the sol-gel method. X-ray diffraction analyses showed that all the samples had a single-phase orthorhombic structure. By analyzing magnetic parameters on the basis of the O2p itinerant electron model, we found that there are two magnetic transition temperatures, TCM and TCP, corresponding to changes in the magnetic ordering for the Mn and Pr cations, respectively. The magnetic moments of Mn3+ and Cr3+ cations within the B sublattice show canted ferromagnetic coupling, and the magnetic moments of the Pr cations within the A sublattice also show canted ferromagnetic coupling. However, the total magnetic moment of the A sublattice shows antiferromagnetic coupling against that of the B sublattice. The assumption of the canted ferromagnetic coupling within the B sublattice was confirmed using magnetoresistance experimental results.

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Section: Results and Analysissupporting

confidence: 68%

Section: O2p Itinerant Electron Modelmentioning

confidence: 99%

Study of magnetic ordering in the perovskite manganites Pr0.6Sr0.4CrxMn1-xO3

et al. 2017

AIP Advances

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“…For example, an antiferromagnetic structure in which the magnetic moments of Ti 2+ (3d 2 ) and Ti 3+ (3d 1 ) cations are antiparallel to those of divalent and trivalent Fe and Ni in a given sublattice, was observed by magnetic measurement in two series of Ti‐doped Ni 0.68 Fe 2.32 O 4 ferrite samples . Likewise it was observed in infrared spectra of M Fe 2 O 4 ( M = Fe, Co, Ni, Cu, and Cr) ferrite samples that the magnetic moments of Cr 2+ (3d 4 ) cations are antiparallel to those of Fe 2+ (3d 6 ) cations in the [B] sublattice .…”

Section: Introductionmentioning

confidence: 86%

“…In order to explain these puzzles, and considering the fact that the spin directions of 3d electrons in the cations are constrained by Hund's rules and that the spin direction of the itinerant electrons is constant, our group proposed that the magnetic moment directions of the cations with 3d electron number n d ≤ 4 (such as Ti 2+ , Ti 3+ , Cr 2+ , Cr 3+ , and Mn 3+ ), are antiparallel to those of the cations with n d ≥ 5 (such as divalent and trivalent Fe, Co, Ni, and Cu) whether at the (A) sites or at the [B] sites of the spinel ferrites . In the following, this assumption is referred to as the “constraint from Hund's rules.” This kind of antiferromagnetic structure has been observed by our group.…”

Section: Introductionmentioning

confidence: 99%

Antiferromagnetic coupling between Mn³⁺and Mn²⁺cations in Mn‐doped spinel ferrites

et al. 2015

Physica Status Solidi (b)

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Ferrite powder samples of Mn x Ni 1-x Fe 2 O 4 (0.0 x 1.0) with single phase (A)[B] 2 O 4 spinel structure were prepared using a sol-gel method. Following the successful proposal by our group, that the magnetic moment directions of Cr 2þ (3d 4 ) cations are antiparallel to those of Fe 3þ (3d 5 ) and Fe 2þ (3d 6 ) cations in a given sublattice of the Cr-doped spinel ferrites due to the constraints imposed by Hund's rules, we extend here the same idea and assume that the magnetic moment directions of Mn 3þ (3d 4 ) cations are also antiparallel to those of Mn 2þ (3d 5 ) and divalent and trivalent Fe (Ni) cations in a given sublattice of Mn-doped spinel ferrites. We have thereby obtained cation distributions for the samples by fitting the magnetic moments of the samples at 10 K. The results indicate that 72% of the Mn cations occupy the [B] sites in MnFe 2 O 4 , which is close to the results for Ni (82%) in NiFe 2 O 4 , but is different from the result obtained using the conventional view which yields 80% of the Mn cations in the (A) sites of MnFe 2 O 4 . On the basis of the present analyses of the magnetic structure of Mn x Ni 1-x Fe 2 O 4 (0.0 x 1.0), we propose here a new model for spinel ferrites that is distinctly different from both the super-and the doubleexchange model and that we refer to as the O2p itinerant electron model. Using this model, not only can the magnetic structure of the spinel ferrites MFe 2 O 4 (M ¼ Fe, Co, Ni, and Cu) be explained better than by using the super-and doubleexchange interaction models, but also the magnetic structure and the cation distributions of Cr-, Mn-, and Ti-doped spinel ferrites can be explained.

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“…6,7 The influence of Cr-doping on the crystal structure and physical properties of spinel ferrites have been reported in many studies, but the Cr ion distributions have been disputed. [8][9][10][11][12][13][14][15] Pervaiz et al 8 In order to explain these discrepancies, our group proposed an O2p itinerant electron model, [16][17][18][19][20][21][22][23] which contains three factors: (i) There are O2p holes in the outer orbits of oxygen anions. 24 In a given sublattice, an O2p electron with constant spin direction can hop to the O2p hole of an adjacent oxygen anion with a metal cation acting as intermediary.…”

Section: Introductionmentioning

confidence: 99%

Magnetic moment directions and distributions of cations in Cr (Co) substituted spinel ferrites Ni0.7Fe2.3O4

Lang

et al. 2015

AIP Advances

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Powder samples of the spinel ferrites MxNi0.7−xFe2.3O4 (M = Cr, Co and 0.0 ≤ x ≤ 0.3) and CrxNi0.7Fe2.3−xO4 (0.0 ≤ x ≤ 0.3) were synthesized using the chemical co-precipitation method. The XRD spectra confirmed that the samples had a single-phase cubic spinel structure. Magnetic measurements showed that the magnetic moments (μexp) per formula both at 10 K and 300 K increased with Co substitution, while the values of μexp decreased with Cr substitution. Applying the assumption that the magnetic moments of Cr2+ and Cr3+ lie antiparallel to those of the divalent and trivalent Fe, Co, and Ni cations in the same sublattice of spinel ferrites, these interesting behaviors could be easily interpreted. The cation distributions of the three series of samples were estimated successfully by fitting the dependences of μexp, measured at 10 K, on the doping level x, using a quantum-mechanical potential barrier model earlier proposed by our group. The results obtained for the Cr cation distributions at the (A) and [B] sites are very close to those obtained elsewhere using neutron diffraction.

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Evidence from infrared spectra for the magnetic moment directions of CR cations in the spinel ferrites

Cited by 24 publications

References 34 publications

Study of magnetic ordering in the perovskite manganites Pr0.6Sr0.4CrxMn1-xO3

Study of magnetic ordering in the perovskite manganites Pr0.6Sr0.4CrxMn1-xO3

Antiferromagnetic coupling between Mn³⁺and Mn²⁺cations in Mn‐doped spinel ferrites

Magnetic moment directions and distributions of cations in Cr (Co) substituted spinel ferrites Ni0.7Fe2.3O4

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Evidence from infrared spectra for the magnetic moment directions of CR cations in the spinel ferrites

Cited by 24 publications

References 34 publications

Study of magnetic ordering in the perovskite manganites Pr0.6Sr0.4CrxMn1-xO3

Study of magnetic ordering in the perovskite manganites Pr0.6Sr0.4CrxMn1-xO3

Antiferromagnetic coupling between Mn3+and Mn2+cations in Mn‐doped spinel ferrites

Magnetic moment directions and distributions of cations in Cr (Co) substituted spinel ferrites Ni0.7Fe2.3O4

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Antiferromagnetic coupling between Mn³⁺and Mn²⁺cations in Mn‐doped spinel ferrites