Anomalous magnetic properties and magnetic phase diagram of La1-xBaxMnO3

The phase diagram of colossal magnetoresistive compounds La1-xBaxMnO3 (0 less than or equal to x less than or equal to 1) was obtained for the first time through magnetization (5 K less than or equal to T less than or equal to 360 K, - 7T less than or equal to H less than or equal to 7T) and resistivity (100 K less than or equal to T less than or equal to 400 K) measurements. Unexpectedly, La1-xBaxMnO3 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 La1-xBaxMnO3 compounds. (C) 2000 Elsevier Science B.V. All rights reserved.