Anomalous Mössbauer fraction in small magnetic particles due to magnetostriction

Mohie-Eldin, M. E. Y.; Gunther, Leon

doi:10.1016/0304-8853(93)90050-c

Cited by 6 publications

(3 citation statements)

References 18 publications

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“…Differ ences [10] between the anisotropy constants ob tained from superparamagnetic relaxation spec tra, and those obtained from the fit of hyperfine fields, as a function of temperature, using collec tive magnetic excitation theory, based on uniaxial symmetry, indicated that PIC and ferritin possess magnetic anisotropy energy which is not strictly uniaxial. This, as we have proposed [56][57][58], is intimately connected with the magnetostriction mechanism, which, we believe, is causing the f factor anomaly.…”

Section: Discussionsupporting

confidence: 57%

A comparison of the magnetic properties of polysaccharide iron complex (PIC) and ferritin

Mohie-Eldin

Frankel

Gunther

1994

Journal of Magnetism and Magnetic Materials

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The synthetic polysaccharide iron complex (PIC) molecule has been suggested as a 'biomimic', i.e. a counterpart, to the naturally occurring biological molecule ferritin with respect to its magnetic properties based on the identification of ferrihydrite as the major mineral in both. Magnetization measurements were used to investigate the magnetic properties of PIC in relation to those of ferritin, as well as to identify differences in such properties between naturally occurring ferritin, which we designate here as Ferritin-I, and ferritin with an artificially high content of Fe 2 + ions bound to its core, which is designated here as Ferritin II. The anisotropy constants K, blocking temperatures TB' magnetic moments m per particle, and number of magnetic moments 'spins' per particle-N sp were found to fit the following relations for PIC and ferritin: K(Ferritin I) < K(PIC) ::s; K(Ferritin 11), TB(FerritinThe magnetic moment per Fe ion was found to be smaller in PIC than Ferritin II due to a stronger antiferromag netic interaction between the Fe ions of PIC. Susceptibility measurements indicated the existence of superantiferro magnetism in PIC and Ferritin I and also showed that most Fe 2 + ions in Ferritin II are bound to its core surface. The enhanced values of K and TB as well as the reduced effect of superantiferromagnetism and the antiferromag netic interaction between the molecules at low temperatures for the Ferritin II indicates the importance of the surface magnetic moments in dominating the magnetic behavior of both PIC and femtin (Ferritin I).

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Section: Discussionsupporting

confidence: 57%

A comparison of the magnetic properties of polysaccharide iron complex (PIC) and ferritin

Mohie-Eldin

Frankel

Gunther

1994

Journal of Magnetism and Magnetic Materials

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“…The experimental results indicate (section 5.2.1) that PIC and ferritin possess a magnetic anisotropy energy which is not strictly uniaxial. We have proposed [43][44][45] a mechanism involving magnetostriction as a theoretical basis of the anomaly, concisely: superparamagnetic relaxation brings about a dynamical displacement of the Mrssbauer nucleus through magnetostriction. These displacements produce a Doppler broadening of the Mfssbauer spectrum.…”

Section: Resultsmentioning

confidence: 99%

The anomalous Mössbauer fraction of ferritin and polysaccharide iron complex (PIC)

et al. 1995

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“…It is commonly reported [1][2][3][4] that ferritin becomes antiferromagnetic (AF), although the evidence is largely indirect and the Nèel temperature reported varies widely in the range 50 K < TN < 240 K. Moreover, for T < 30 K, magnetization measurements give evidence of superparamagnetic relaxation and of spin freezing of the total magnetic moment associated with the uncompensated spins at the boundary of the cluster of iron ions [5]. Recently, interest in the magnetic behavior of ferritin has been revived by the confirmation [6,7] of an early report [8] of the occurrence of macroscopic quantum coherence phenomena at low temperature.…”

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confidence: 99%

Proton NMR and susceptibility measurements on the magnetic core of ferritin

et al. 2000

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We report an investigation of the magnetic core of the biomolecule ferritin by means of proton nuclear magnetic resonance (NMR) and relaxation, magnetic susceptibility and scanning electron microscope (SEM) measurements. SEM images show that the outer protein shell is taken out completely by an appropriate chemical treatment and indicate particle sizes ranging from 10' -to 104 nm. Susceptibility measurements show a maximum in the zero-field-cooled data which is strongly field-dependent and can be ascribed to superparamagnetic behavior, whereas the hysteresis curve is different from normal ferritin. Proton NMR and spin-lattice relaxation data as a function of temperature at 4.7 T suggest the presence of an antiferromagnetic transition around 100 K.Ferritin is a biomolecule of interest in the problem of iron storage in living organisms. It is commonly reported [1-4] that ferritin becomes antiferromagnetic (AF), although the evidence is largely indirect and the Nèel temperature reported varies widely in the range 50 K < TN < 240 K. Moreover, for T < 30 K, magnetization measurements give evidence of superparamagnetic relaxation and of spin freezing of the total magnetic moment associated with the uncompensated spins at the boundary of the cluster of iron ions [5]. Recently, interest in the magnetic behavior of ferritin has been revived by the confirmation [6,7] of an early report [8] of the occurrence of macroscopic quantum coherence phenomena at low temperature. The main purpose of the present paper is to investigate the spin dynamics of the Fei+ magnetic moments in the ferritin core by means of proton nuclear magnetic resonance (NMR) and relaxation measurements. Since in the naturally occurring ferritin biomolecule the largest number of protons is contained Permanent address:

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Anomalous Mössbauer fraction in small magnetic particles due to magnetostriction

Cited by 6 publications

References 18 publications

A comparison of the magnetic properties of polysaccharide iron complex (PIC) and ferritin

A comparison of the magnetic properties of polysaccharide iron complex (PIC) and ferritin

The anomalous Mössbauer fraction of ferritin and polysaccharide iron complex (PIC)

Proton NMR and susceptibility measurements on the magnetic core of ferritin

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