КОЛОССАЛЬНЫЙ МАГНИТОРЕЗИСТИВНЫЙ ЭФФЕКТ В КОБАЛЬТИТАХ СО СТРУКТУРОЙ ПЕРОВСКИТА

The magnetic and magnetotransport properties of the La 0.45 Ba 0.55 CoO 3–x cobaltites have been studied as a function of oxygen content. It is shown that the decrease in the oxygen content leads to strong enhancement of the magnetoresistance and the metamagnetic behavior. It is suggested that the colossal magnetoresistance results from the spin state transition induced by an external magnetic field.