Magnetoresistance Effect of Non-stoichiometric (La_(0.8)Sr_(0.2))_(0.7)MnO_3 Perovskite Manganite

Magnetic properties and magnetoresistance effect of polycrystalline perovskite manganites (La0.8Sr0.2)0.7 MnO3 have been investigated by measuring the resistivity, magnetization curves and Curie temperature of samples. The sample exhibits composite structure of magnetic perovskite phase and Mn3O4 phase . The resistivity vs temperature ρ ( T ) curves presents a duo-peak behavior. The temperature stability of the magnetoresistance ratio of the (La0.8Sr0.2)0.7 MnO3 sample, compared to that of stoichiometric La0.8Sr0.2MnO3, has been improved remarkably. The magnetoresistance ratio almost keeps unchanged in a relatively wide temperature range from 220 K to 320 K, which is feasible for magnetoresistive sensor application.