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 arПоказать полностьюe 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