Polishchuk D. Magnetic and resonance properties of inhomogeneous macro- and nanomagnetics based on manganese and iron.

The work is aimed at the investigation of the regularities of changes in properties of magnetic systems based on manganese and iron under the influence of structural inhomogeneity, coherent strains and nanostructuring. The main results have been received with the use of electron spin resonance technique, which was additionally supplied by structural and magnetometric measurements. The transformation of magnetic state of the polycrystalline system La2/3Ba1/3MnO3 has been studied in the vicinity of the structural phase transition: magnetic phase separation has been revealed, and parameters of each phase have been calculated. In thin films (La,Na)MnO3, grown on single-crystal LaAlO3 (001) substrates, coexistence of two kinds of ferromagnetic regions has been observed. The parameters of the coexisting regions have been determined and explanation for their appearance has been provided. Peculiar features of magnetic behavior of planar arrays of Fe nanowires (NW) have been characterized. Conclusions on a mechanism of magnetization reversal in NWs have been made on the basis of computer simulations of hysteresis loops and their comparison with the experimental ones. Unidirectional anisotropy has been revealed, and its time-dependent changes have been analyzed.