Magnetic properties and the mechanism of formation of the uncompensated magnetic moment of antiferromagnetic ferrihydrite nanoparticles of a bacterial origin

Balaev, D. A.; Krasikov, A. A.; Dubrovskiĭ, A. A.; Semenov, S.; Bayukov, O. A.; Stolyar, S. V.; Исхаков, Р. С.; Ладыгина, В. П.; Ishchenko, L. A.

doi:10.1134/s1063776114080044

Cited by 39 publications

(21 citation statements)

References 34 publications

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“…Typical microphotographs were presented in [32,34]). According to our data, the <d> values are consistent with those obtained from the magnetization curves at T > TB [23,24,32].…”

Section: Samplessupporting

confidence: 89%

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Exchange bias in nano-ferrihydrite

Balaev

Krasikov

Dubrovskiy

et al. 2016

Journal of Applied Physics

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We report the results of investigations of the effect of cooling in an external magnetic field starting from the temperature over superparamagnetic blocking temperature TB on the shift of magnetic hysteresis loops in systems of ferrihydrite nanoparticles from ~2.5 to ~5 nm in size with different TB values. In virtue of high anisotropy fields of ferrihydrite nanoparticles and open hysteresis loops in the range of experimentally attainable magnetic fields, the shape of hysteresis loops of such objects in the field-cooling mode is influenced by the minor hysteresis loop effect.A technique is proposed for distinguishing the exchange bias effect among the effects related to the minor hysteresis loops caused by high anisotropy fields of ferrihydrite particles. The exchange bias in ferrihydrite is stably observed for particles no less than 3 nm in size or with TB over 40 K, and its characteristic value increases with the particle size.

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“…Typical microphotographs were presented in [32,34]). According to our data, the <d> values are consistent with those obtained from the magnetization curves at T > TB [23,24,32].…”

Section: Samplessupporting

confidence: 89%

“…Hereinafter, the initial sample is denoted as b-fh. Lowtemperature (140−200 0 С) annealing of ferrihydrite leads to an increase in the size of particles due to their partial agglomeration [24,31,32]. The investigated bacterial ferrihydrite samples annealed at different temperatures for different times are denoted as b-fh-a and b-fh-a*.…”

Section: Samplesmentioning

confidence: 99%

Exchange bias in nano-ferrihydrite

Balaev

Krasikov

Dubrovskiy

et al. 2016

Journal of Applied Physics

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“…The precipitate was collected on a filter, washed, and dried at room temperature. Low-temperature annealing was performed in a drying oven at a temperature of ~170 0 C for 3 and 24 h, as was described in [13,14]. Hereinafter, the samples are marked in accordance with the annealing time in hours, i.e., S-FH(Co)-0h, S-FH(Co)-3h, and S-FH(Co)-24h.…”

Section: Methodsmentioning

confidence: 99%

Modification of the Structure and Magnetic Properties of Cobalt-Doped Ferrihydrite Nanoparticles Under Heat Treatment

Stolyar

Balaev

Krasikov

et al. 2017

J Supercond Nov Magn

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Nanoparticles of antiferromagnetic materials acquire the magnetic moment due to the surface effects and structural defects. According to the Neel hypothesis, magnetic moment P of a particle containing N magnetically active atoms with magnetic moment J can be estimated as P ~ J•N n or P ~ V n , where V is the particle volume. Numerous studies of the magnetic properties of ferrihydrite 5Fe2O3•9H2O and ferritin revealed a value of n ≈ ½ for this material, in which Fe atoms have the octahedral surrounding of anions. We investigate the effect of low-temperature annealing of cobalt-doped ferrihydrite nanoparticles on their average size and magnetic properties. Using the Mössbauer spectroscopy study, we demonstrate that doping with Со makes Fe atoms enter the anion tetrahedra, which leads to an increase in the exponent n > ½ in the expression P ~ J•N n .

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“…As it turned out, the magnetic properties of biogenic nanoparticles of ferrihydrite can be modified by heat treatment [5], however, it is not possible to produce a stable sol on the basis of annealed powders. As a matrix for the preparation of stable sols based on chemically produced ferrihydrite powders, it is possible to use organic preparations such as water-soluble proteins albumin or natural polysaccharide arabinogalactan.…”

Section: Introductionmentioning

confidence: 99%