Magnetic phase boundary and transport properties of La0.67Ca0.33MnO3

The effects of Fe3O4 magnetic phase and its doping level on the electric transport and magnetic properties of La0.67Ca0.33MnO3 were investigated, where the Fe3O4 doping level was 0, 0.1, 0.5, 1, 7.5, and 20%. A twofold effect, enhancement and suppression, on magnetization properties was observed in the La0.67Ca0.33MnO3/Fe3O4 composites. For a low field ranging from 0 to 0.3 T an obvious enhanced magnetization was observed, while for a higher field a suppressed magnetization was observed. A new insulator–metal transition behaviour was observed for all the composites. Compared with pure La0.67Ca0.33MnO3, the twofold influence and new transition were discussed by considering the separation and pinning effects of the Fe3O4 on the growth and rotation of La0.67Ca0.33MnO3 ferromagnetic domain. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)