Magnetoresistance Behavior of La_(2-x)/3Bi_x/3Ca_l/3MnO₃ (x = 0.4)

The magnetoresistance (MR) behavior of La_(2-x)/3Bi_x/3Ca_l/3MnO₃ (x = 0.4) compound was investigated. The compound exhibits complex magnetic transitions, i. e., paramagnetic-canted ferromagnetic-ferromagnetic-spin glass transitions. The temperature dependence of resistivity of the compound indicates a semiconducting behavior, and no semiconductor-metal transition was associated with these magnetic transitions. The magnetoresistance ratio exhibits a critical maximum corresponding to the canted ferromagnetic transition. A MR ratio as large as 86% was observed at 85 K. The temperature dependence of MR ratio is well described by the relation of ( ρ_o -ρH ) / ρ_o = A(M/M_s)².