Electrical and magnetic properties of non-stoichiometric (La_(0.8)Sr_(0.2)_(1-x))MnO_3 perovskites

摘要

The structure, transport and magnetic properties of (La_(0.8)Sr_(0.2))_(1-x)MnO_3 (0 ≤ x ≤ 0.30) polycrystalline perovskite manganites have been investigated. For all the samples the Curie temperatures, T_c, remain nearly unchanged (329 ± 3 K). Resistivity versus temperature curves for the samples show a double-peak behavior. A significant magnetoresistance (MR) effect and different temperature dependences of the MR ratios of the samples are observed. The shapes of the MR-T curves of the samples can be adjusted by changing x. For the x = 0.30 sample, a nearly constant MR ratio of (9.5 ± 0.5)% is obtained over the temperature range from 205 to 328 K.