Oxygen-redistribution-induced disorder and magnetotransport properties of Sm0.55Sr0.45MnO3 manganites

The authors studied the effects of oxygen-redistribution-induced disorder on the magnetotransport of Sm0.55Sr0.45MnO3 manganites near the metal-insulator transition. Oxygen redistribution in the sample was obtained by annealing at 325 degrees C 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. (c) 2006 American Institute of Physics.