Magnetic behaviour of bismuth substituted perovskites La1-xBixMn0.8Co0.2O3

DC magnetization measurements have been made on two systems with 30 atomic% and 50 atomic% substitutions of Bi for La in the perovskite LaMn0.8Co0.2O3. At 50 atomic% substitution the system switches over from hexagonal to orthorhombic structure. The two systems are ferromagnetic and the Curie temperature decreasing with increasing substitution of Bi; showing weakening of ferromagnetism. Departures between magnetization (M) - temperature (T) curves and observed dynamic relaxation are indicative of magnetic disorder. However, for both the samples the magnetic field (upto 1 kOe) does not show a marked effect on the peak temperature, Tm in M - T curves recorded in zero field cooling mode. (author)