Oxygen Stoichiometry Modification by O₂ - Plasma Treatment in La0.7Ca0.3MnO₃-δ

Oxygen-plasma effects of single crystal and thin film samples of La_(0.7)Ca_(0.3)MnO_(3-δ) have been studied. Our resistivity measurements indicate that oxygen plasma treatment gives rise to oxygen diffusion into bulk regions, which results in a decrease of Mn³+ concentration in oxygen nonstoichiometric La_(0.7)Ca_(0.3)MnO_(3-δ) and in the activation energies of Holstein's small polarons in the paramagnetic region.