Сибирский федеральный университет

Тип публикации: статья из журнала

Год издания: 2014

Идентификатор DOI: 10.1134/S1063776114080044

Ключевые слова: Antiferromagnetism, Bacteria, Magnetic materials, Magnetic moments, Magnetic properties, Magnetism, Nanomagnetics, Nanoparticles, Superparamagnetism, Antiferromagnetic orderings, Antiferromagnetics, Average magnetic moments, Klebsiella oxytoca, Magnetically actives, Magnetization curves, Mechanism of formation, Superparamagnetic blocking, Magnetic bubbles

Аннотация: The magnetic properties of the superparamagnetic ferrihydrite nanoparticles that form as a result of the vital activity of Klebsiella oxytoca bacteria are studied. Both an initial powder with an average number of iron atoms N (Fe) similar to 2000-2500 in a particle and this powder after annealing at 140A degrees C for 3 h in air are investigated. The following substantial modifications of the magnetic properties of the ferrihydrite nanoparticles are detected after annealing: the superparamagnetic blocking temperature increases from 23 to 49.5 K, and the average magnetic moment of a particle increases (as follows from the results of processing of magnetization curves). The particles have antiferromagnetic ordering, and the magnetic moment resulting in the superparamagnetism of the system appears due to random spin decompensation inside the particle. For this mechanism, the number of uncompensated spins is proportional to the number of magnetically active atoms raised to the one-half power, and this relation holds true for the samples under study at a good accuracy. The possible causes of the detected shift of magnetic hysteresis loops at low temperatures upon field cooling are discussed.

Журнал: JOURNAL OF EXPERIMENTAL AND THEORETICAL PHYSICS

Выпуск журнала: Vol. 119, Is. 3

Номера страниц: 479-487

ISSN журнала: 10637761

Место издания: NEW YORK

Издатель: MAIK NAUKA/INTERPERIODICA/SPRINGER

• Balaev D.A. (Siberian Federal University)
• Dubrovskii A.A. (Kirenskii Institute of Physics, Siberian Branch, Russian Academy of Sciences)
• Semenov S.V. (Siberian Federal University)
• Bayukov O.A. (Kirenskii Institute of Physics, Siberian Branch, Russian Academy of Sciences)
• Stolyar S.V. (Siberian Federal University)
• Iskhakov R.S. (Kirenskii Institute of Physics, Siberian Branch, Russian Academy of Sciences)
• Krasikov A.A. (Siberian Federal University)
• Ishchenko L.A. (Siberian Federal University)
• Ladygina V.P. (International Scientific Center of Extreme States of Organisms, Krasnoyarsk Scientific Center, Siberian Branch, Russian Academy of Sciences)

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