The cobaltites derived from LaCoO3 are prospective materials for their electronic and catalytic properties and represent also fundamental interest because of the temperature and pressure driven transitions between Co(III) ionic states of different spin numbers. The aim of the project is to investigate novel phenomenon where itinerant charge carriers convert the surrounding diamagnetic Co(III) states into magnetic ones, forming large spin polarons. In the frame of this project, new electron and hole doped cobaltites, including the mixed Co/Ni and Co/Cu systems, will be prepared and their structural, magnetic and electric transport properties will be studied over the range of low and high temperatures. The observed data will be confronted with theoretical band structure calculations treating the polarons as impurity using the supercell or impurity models. It is expected that this project will provide a better microscopic description of transport phenomena in mixed-valency oxides close to the boundary between the regime of localized and itinerant electrons.
