Oxygen-redistribution-induced disorder and magnetotransport properties of Sm_(0.55)Sr_(0.45)MnO_3 manganites

摘要

The authors studied the effects of oxygen-redistribution-induced disorder on the magnetotransport of Sm_(0.55)Sr_(0.45)MnO_3 manganites near the metal-insulator transition. Oxygen redistribution in the sample was obtained by annealing at 325℃ in vacuum. The temperature dependences of resistivity and magnetoresistance were measured as a function of the annealing time. The authors observed a dramatic increase in the magnitude of the resistivity peak at the metal-insulator transition and a reduction of its width after an initial short-time annealing, followed by a logarithmic increase of the resistivity with annealing time. The data agree qualitatively with phase-separation theories for colossal magnetoresistance manganites.