Тип публикации: статья из журнала
Год издания: 2015
Идентификатор DOI: 10.1016/j.jallcom.2015.04.067
Ключевые слова: Warwickites, Spin-glass, Mossbauer spectroscopy, Anisotropy, Glass, Glass transition, Magnetic susceptibility, Magnetism, Magnetocrystalline anisotropy, Single crystals, Temperature, Dynamical scaling theory, Magnetic susceptibility measurements, Magnetic transitions, Non-equivalent sites, Spin-freezing temperature, Ssbauer spectroscopies, Superparamagnetic behavior, Spin glass
Аннотация: Single crystals of MgFeBO4 and CoFeBO4 warwickites were obtained. The effects of charge ordering and magnetic properties were investigated by Mossbauer spectroscopy. Cation distribution over M1 and M2 nonequivalent sites and the average charge at the metal positions were established. Low temperature Mossbauer spectra reveal spin-glПоказать полностьюass behavior, with spin-freezing temperatures T-SG of 15.2 and 33.2 K for Mg-and Co-warwickites, respectively, higher than that observed from the d.c. and a.c. magnetic susceptibility measurements. The difference is explained in terms of dynamical scaling theory. The specific shape of the Mossbauer spectra in the vicinity of the magnetic transition at T-SG shows the difference between spin-glass and superparamagnetic behavior and demonstrates an overwhelming role of the exchange anisotropy in the properties of Mg-warwickite. In Co-warwickite the increase of magnetocrystalline anisotropy provokes an increase in magnetic viscosity. (C) 2015 Elsevier B.V. All rights reserved.
Журнал: JOURNAL OF ALLOYS AND COMPOUNDS
Выпуск журнала: Vol. 642
Номера страниц: 204-209
ISSN журнала: 09258388
Место издания: LAUSANNE
Издатель: ELSEVIER SCIENCE SA