Review of the low-temperature magnetic properties of magnetite from a rock magnetic perspective

Muxworthy, Adrian R.; McClelland, E.

doi:10.1046/j.1365-246x.2000.00999.x

Cited by 198 publications

(161 citation statements)

References 80 publications

Supporting

Mentioning

148

Contrasting

Unclassified

Order By: Relevance

“…4A) showed a monotonic drop in remanence from room temperature to 10 K, a superimposed weak Verwey transition in the field cool (FC) curve at 118 Ϯ 2 K, and ␦ FC ͞␦ ZFC ϭ 1.1, where ZFC is the zero FC. These data are consistent with most of the magnetism in this sample originating from a paramagnet [almost certainly the lepidocrocite, whose 50-K Néel point (20) would account for the observed steep drop in remanence to 50 K] along with a small fraction from magnetite in the SD or larger size range. That magnetite is quite pure: Fe 3-x Z x O 4 with x Ϸ0.01-0.04 for a wide range of impurities; Z ϭ Zn, Ti, Al, Mg, Co, Ni, and Ga (20 -23).…”

Section: Results and Discussion Formation Of Lepidocrocite (␥-Feooh)supporting

confidence: 84%

Formation of tabular single-domain magnetite induced by Geobacter metallireducens GS-15

Vali

Weiss

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

103

View full text Add to dashboard Cite

Distinct morphological characteristics of magnetite formed intracellularly by magnetic bacteria (magnetosome) are invoked as compelling evidence for biological activity on Earth and possibly on Mars. Crystals of magnetite produced extracellularly by a variety of bacteria including Geobacter metallireducens GS-15, thermophilic bacteria, and psychrotolerant bacteria are, however, traditionally not thought to have nearly as distinct morphologies. The size and shape of extracellular magnetite depend on the culture conditions and type of bacteria. Under typical CO2-rich culture conditions, GS-15 is known to produce superparamagnetic magnetite (crystal diameters of approximately <30 nm). In the current study, we were able to produce a unique form of tabular, single-domain magnetite under nontraditional (low-CO 2) culture conditions. This magnetite has a distinct crystal habit and magnetic properties. This magnetite could be used as a biosignature to recognize ancient biological activities in terrestrial and extraterrestrial environments and also may be a major carrier of the magnetization in natural sediments.

show abstract

Section: Results and Discussion Formation Of Lepidocrocite (␥-Feooh)supporting

confidence: 84%

Formation of tabular single-domain magnetite induced by Geobacter metallireducens GS-15

Vali

Weiss

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

103

View full text Add to dashboard Cite

show abstract

“…The medium consisted of an artificial sea water ͑ASW͒ base, 22 to which was added ͑per liter͒ prior to autoclaving: 0.2 ml 0.2% aqueous resazurin, 5.0 ml modified Wolfe's mineral elixir, 23,36 0.5 g sodium succinateϫ 6H 2 O, 0.2 g sodium acetateϫ 3H 2 O, 0.5 g CasAmino Acids ͑Difco Laboratories, Detroit, MI, USA͒, 0.25 g NH 4 Cl, and 100 l 0.2% ͑w/v͒ aqueous resazurin. The pH of the medium was adjusted to 7.0.…”

Section: Strain Mv-1 (Including Mutant)mentioning

confidence: 99%

“…Cells were grown microaerobically in 850 ml of media in 2 l glass bottles. The medium consisted of the same ASW base as described above, to which was added ͑per liter͒ prior to autoclaving: 5 ml modified Wolfe's mineral elixir, 0.25 g NH 4 Cl, and 100 l 0.2% ͑w/v͒ aqueous resazurin. The pH of the medium was adjusted to 7.0, and 1.07 g NaHCO 3 was added.…”

Section: Strains Mc-1 and Mms-1mentioning

confidence: 99%

“…The literature on the Verwey transition is vast, and we refer the reader to several reviews. [3][4][5][6] Magnetite has an inverse spinel crystal structure, Fe 3 O 4 = ͓Fe 3+ ͔ A ͓Fe 3+ Fe 2+ ͔ B O 4 , where A sites are coordinated in tetrahedra and B sites are coordinated in octahedra. Magnetic order at the A and B sites is antiparallel, resulting in ferrimagnetism with an excess magnetic moment of about 4 B per formula.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic irreversibility and the Verwey transition in nanocrystalline bacterial magnetite

Prozorov

Mallapragada

et al. 2007

Phys. Rev. B

View full text Add to dashboard Cite

The magnetic properties of biologically produced magnetite nanocrystals biomineralized by four different magnetotactic bacteria were compared to those of synthetic magnetite nanocrystals and large, high-quality single crystals. The magnetic feature at the Verwey temperature TV was clearly seen in all nanocrystals, although its sharpness depended on the shape of individual nanoparticles and whether or not the particles were arranged in magnetosome chains. The transition was broader in the individual superparamagnetic nanoparticles for which TB < TV, where TB is the superparamagnetic blocking temperature. For nanocrystals organized in chains, the effective blocking temperature TB > TV and the Verwey transition is sharply defined. No correlation between particle size and TV was found. Furthermore, measurements of M (H,T,time) suggest that magnetosome chains behave as long magnetic dipoles where the local magnetic field is directed along the chain. This result confirms that time-logarithmic magnetic relaxation is due to the collective (dipolar) nature of the barrier for magnetic moment reorientation. The magnetic properties of biologically produced magnetite nanocrystals biomineralized by four different magnetotactic bacteria were compared to those of synthetic magnetite nanocrystals and large, high-quality single crystals. The magnetic feature at the Verwey temperature T V was clearly seen in all nanocrystals, although its sharpness depended on the shape of individual nanoparticles and whether or not the particles were arranged in magnetosome chains. The transition was broader in the individual superparamagnetic nanoparticles for which T B Ͻ T V , where T B is the superparamagnetic blocking temperature. For nanocrystals organized in chains, the effective blocking temperature T B Ͼ T V and the Verwey transition is sharply defined. No correlation between particle size and T V was found. Furthermore, measurements of M͑H , T , time͒ suggest that magnetosome chains behave as long magnetic dipoles where the local magnetic field is directed along the chain. This result confirms that time-logarithmic magnetic relaxation is due to the collective ͑dipolar͒ nature of the barrier for magnetic moment reorientation.

show abstract

“…In addition, below T V there is large increase in the intensity of the magnetocrystallographic anisotropy and a change in its symmetry [19,20]. There are also corresponding changes in many other magnetic properties [17,21].…”

Section: Introductionmentioning

confidence: 99%

Low-temperature viscous magnetization of multidomain magnetite: Evidence for disaccommodation contribution

Muxworthy

Williams

2006

Journal of Magnetism and Magnetic Materials

View full text Add to dashboard Cite

Low-temperature viscous acquisition and decay measurements above and below the Verwey transition have been measured for a selection of natural and synthetic multidomain magnetite samples. A strong correlation between the viscosity spectra and published disaccommodation spectra was found, where disaccommodation reflects electron mobility. Assuming the viscosity is controlled by identical mechanisms as disaccommodation, the reduction in electron mobility below the Verwey transition is found to significantly increase viscous acquisition and decay rates over the time scales measured (1-3000 seconds). Although strongly affecting the viscosity, disaccommodation processes do not appear to control the rate of change of viscosity with time, i.e., the viscosity curvature. It is suggested that the curvature is controlled by the shape of relaxation-time distributions, which is approximately the same for all the magnetite samples studied. In addition, the acquisition and decay curvature parameters mirror each other when plotted as a function of temperature, inferring that at any given temperature the acquisition and decay processes are identical.PAC numbers: 75.60.Lr, 75.60.Ch, 9.60.Pn.

show abstract

Review of the low-temperature magnetic properties of magnetite from a rock magnetic perspective

Cited by 198 publications

References 80 publications

Formation of tabular single-domain magnetite induced by Geobacter metallireducens GS-15

Formation of tabular single-domain magnetite induced by Geobacter metallireducens GS-15

Magnetic irreversibility and the Verwey transition in nanocrystalline bacterial magnetite

Low-temperature viscous magnetization of multidomain magnetite: Evidence for disaccommodation contribution

Contact Info

Product

Resources

About