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Morin, François

doi:10.1103/physrev.78.819.2

Cited by 593 publications

(247 citation statements)

References 5 publications

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“…Its hyperfine parameters are very close to those reported by Randrianantoandro et al 8 for ball-milled hematite. It is significant that the area ratio at 6 K shown by the two different magnetic components is nearly the same as that presented at RT ͑see 11 However, by reducing the particle size or introducing substitutional aluminum in bulk hematite, T M decreases or is even suppressed. 30 Mössbauer data, particularly the QS sign, were correlated with the magnetic order in a system of the ␣-(Fe,Al) 2 O 3 type by de Grave et al, 30 with a negative QS implying a WF order.…”

Section: Resultsmentioning

confidence: 90%

“…It is a complex magnetic material, being antiferromagnetic ͑AF͒ at low temperatures and undergoing a transition to a weak ferromagnetic state ͑WF͒ above the so-called Morin temperature (T M Х260 K), because of a spin canting. 11 The hematite magnetic behavior is very sensitive to strain, external fields and, especially, to impurities or foreign atoms. 12 In this sense, some researchers have also investigated the products of hematite milled with different metals and oxides.…”

Section: Introductionmentioning

confidence: 99%

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Phase evolution and magnetic properties of a high-energy ball-milled hematite–alumina system

Cótica

Zanatta

Rocha

et al. 2004

Journal of Applied Physics

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The system (␣-Fe 2 O 3 ) x (␣-Al 2 O 3 ) 1Ϫx was subjected to 24 h of high-energy ball-milling varying its nominal concentration, x. The milled samples were structurally and magnetically characterized at room temperature by x-ray diffraction, Mössbauer spectroscopy, and magnetic measurements. Mössbauer studies were also performed in the temperature range 250-6 K. As a result of the earlier analyses, it was observed that the milling products were extremely dependent on the hematite starting concentration. In samples with low ␣-Fe 2 O 3 initial concentration ͑i.e., xр0.12), the paramagnetic solid solution ␣-(Fe ⌬Y Al 1Ϫ⌬Y ) 2 O 3 , the ␣-Fe and the FeAl 2 O 4 phases were identified, along with alumina, which was always residual. The presence of spinel and metallic iron was attributed to the stainless-steel vial and balls abrasion. For xϾ0.12, the iron component was no longer present but another magnetic component, corresponding to an aluminum-substituted hematite phase, ␣-(Fe 1Ϫ⌬W Al ⌬W ) 2 O 3 , could be seen to increase with increasing x. This solid solution was shown to be transitional, at room temperature, between two ordering states, weak ferromagnetic and superparamagnetic, the latter resulting from the milling induced particle size reduction. Low temperature Mössbauer spectra revealed the magnetic ordering of both solid solutions, ␣-(Fe ⌬Y Al 1Ϫ⌬Y ) 2 O 3 and ␣-(Fe 1Ϫ⌬W Al ⌬W ) 2 O 3 , and indicated the suppression of the Morin transition for the iron-rich solid solution. The magnetization versus magnetic field curves obtained for samples with xу0.12 revealed, besides a general superparamagnetic character, some hysteretic behavior due to the magnetic phases eventually existing.

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Section: Resultsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Phase evolution and magnetic properties of a high-energy ball-milled hematite–alumina system

Cótica

Zanatta

Rocha

et al. 2004

Journal of Applied Physics

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“…The anisotropic interactions are known to play a crucial role in the weak ferromagnetism in α-Fe 2 O 3 [7,8] and RFeO 3 (R = rare-earth) [9,10], the strong magnetoelectric effect in multiferroic materials such as TbMnO 3 [11,12], the reversal magnetization in YVO 3 [13] and the electron spin resonance (ESR) behavior in KCuF 3 [14].…”

Section: Introductionmentioning

confidence: 99%

Effect of orbital symmetry on the anisotropic superexchange interaction

Kim

Min²

2011

New J. Phys.

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“…The Morin magnetic phase transition (Morin, 1950;Shull, Strauser & Wollan, 1951) from the 'easy-plane' weak ferromagnetic state to the 'easy-axis' antiferromagnetic state takes place in hematite at TM =253 K. By measuring the temperature dependence of the 111 magnetic reflection intensity (whose structure factor vanishes in the 'easyaxis' state), it was established that in the investigated crystal the Morin transition occurs in the temperature range of 260-248 K.…”

Section: (4) Effect Of Magnetic Defects On the Amplitude Of Pendelli~mentioning

confidence: 99%

Magnetic Pendellösung effects in neutron scattering by perfect magnetic crystals

Kvardakov¹,

Соменков²

1992

Acta Cryst Sect A

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Pendell6sung effects in magnetic neutron scattering by thin (thickness of the order of the extinction length) crystals of weak ferromagnets FeBO3 and a-Fe203 were investigated. Dynamical oscillations in the scattering intensity dependences on the crystal's effective thickness, temperature and magnetic field orientation have been found. The influence of irregularities in the magnetic structure related to domains, a magnetic phase transition and magnetoelastic oscillations on the Pendell6sung oscillation amplitude has been established. The oscillation amplitude and the scattering intensity dependence on the structure-factor magnitude have been used to obtain information on small deformations from perfection of the crystalline and magnetic structures, which are difficult to detect by other methods.

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Magnetic Susceptibility ofαFe2O3andα

Cited by 593 publications

References 5 publications

Phase evolution and magnetic properties of a high-energy ball-milled hematite–alumina system

Phase evolution and magnetic properties of a high-energy ball-milled hematite–alumina system

Effect of orbital symmetry on the anisotropic superexchange interaction

Magnetic Pendellösung effects in neutron scattering by perfect magnetic crystals

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