Anomalous magnetic properties and magnetic phase diagram of La 1− xBa xMnO 3

Abstract

The phase diagram of colossal magnetoresistive compounds La 1− x Ba x MnO 3 (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− x Ba x MnO 3 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− x Ba x MnO 3 compounds.