Anomalous magnetic properties and magnetic phase diagram of La_1-xBa_xMnO₃

The phase diagram of colossal magnetoresistive compounds La_1-xBa_xMnO₃ (0≤x≤1) was obtained for the first time through magnetization (5 K≤T≤360 K, -7 T ≤H≤7 T) and resistivity (100 K≤T≤400 K) measurements. Unexpectedly, La_1-xBa_xMnO₃ compounds were found to be ferromagnetic for all x with varying magnitude of saturation magnetization (M_S) with theoretically maximum M_S for 0.13<x<0.5 and reduced M_S for both x<0.13 and x>0.5. Near x = 0.5, the ground state changes from single phase ferromagnetic metallic state to multiphase ferromagnetic insulator state. In the two reduced M_S doping regimes of x<0.13 and x>0.5, the former showed an anomalous strong field history-dependent magnetization behavior, but the latter showed a rather conventional field history-dependent magnetization behavior. We discuss the possible causes of these differences and spin structures of La_1-xBa_xMnO₃ compounds.