Search

In this work, we have designed obtained a novel multiferroic nanocomposite using the high-pressure torsion (HPT) method. The crystal structure, phase composition, morphology, ferromagnetic (FM) and ferroelectric (FE) properties of the initial powders and "multiferroic-ferromagnetic" nanocomposites have been studied comprehensively. The initial powders and their composites show the perovskite and spinel crystalline phases for the FE and FM fractions, respectively. After HPT, the particle sizes of the initial powders are decreased significantly. It is shown that the novel nanocomposite consists of exchange-interacting FE and FM phases and demonstrates improved magnetic and electrical properties in low fields at room temperature. A colossal increase in residual polarization with an increase in external high-pressure is found in new composite. The obtained results make it possible to consider the novel nanocomposite as a new functional material for its use both in electronic devices for monitoring ultra-high-pressure and in integrated circuits of high-speed computing nanosystems with low switching energy. The HPT method is a promising method for obtaining new heterophase multiferroic nanosystems., Comment: 37 pages, 14 figures, 6 tables

Despite extensive researches on manganites owing to widespread use in modern electronics, this class of metal oxides does not cease to surprise with its unique properties and new phenomena. Here we have studied structural and magnetic properties of non-Heisenberg manganite nanoparticles with a strong spin-electron coupling. During transition from low temperature ferromagnetic to high temperature paramagnetic state, the change in charge, valence and spin (magnetic moment) with the localization of eg-electrons on the manganese ions have been detected. With decrease in a temperature, the overstated effective magnetic moment of Mn ions in paramagnetic phase is reduced dramatically testifying to spin-dependent magnetism. The critical behavior of magnetization with determination of critical parameters near second-order phase transition has been studied comprehensively. Based on unusual behavior of temperature and field dependences of magnetic entropy change under different magnetic field, an additional influence of superparamagnetism of nanoparticles on the magnetocaloric effect has been found., Comment: Manuscript consists of 26 pages, 6 Figures. Supplementary Material consists of 37 pages, 11 Figures and 12 Tables