Mykhaylov V. Magnetic,transport and resonance properties of self-doped and calcium doped manganoites

In the thesis a result of studies of the excess manganese, pressures and magnetic field effects on transport, magnetic and resonance properties of the ceramic and film manganite samples having compositions La1-хMn1+xO3 and (La0.7Са0.3)1-хМп1+хО3 were obtained. The anomalies on temperature dependences of magnetization and susceptibility were observed at the temperature Т = 45 К in manganites with excess manganese. This is connected with formation of the noncollinear spin structure in clasters of the multivalent manganese ions as a result of competitions AFM super and FM double exchanges. It has been established a linear increasing of the Curie temperature Tc and metal-dielectric transition temperature TMD under pressure. The effects of the pressure and magnetic field stronger reweal itself in film samples than in ceramics. The magnetic and transport studies of ceramic and film (La0.7Cao.3)1-xMnO3 samples have shown that manganese doping increases the area of the ferromagnetic ordering, conductivity as well as values and temperature of MRE peak in doped manganite. Using the explored ferromagnetic resonance (FMR) spectra in longitudial and transversal magnetic fields the easy plane character of the effective magnetic anisotropy and parameters of exchange interaction in the doped manganite films have been determined. For the first time in manganite film Lao ?Mni 3O3 the surface spin-wave modes in spectrum of the spin-wave resonance were found and mechanisms responsible for their origin were considered.