Electronic and magnetic properties of La0.4Ba0.1Ca0.5MnO3-y thin films

We investigated the transport and magnetic properties of La0.4Ba0.1Ca0.5MnO3-y thin films to see the effect of substitution of the small atom Ca by Ba, which is much bigger. La0.4Ba0.1Ca0.5MnO3-y thin films have been fabricated by a pulsed laser deposition technique. The electrical resistance has been measured in the range of 20-200 K under the field from zero up to 9 T. Under zero field, at T similar to 37 K, an insulator-to-metal (IM) transition was observed, as expected. However, we found that the magnetic field dependence of the resistivity seems to be anomalous since T-IM shifts to a lower temperature when the magnetic field is increased and the magnetoresistance at low temperature is positive. Magnetization measurements imply that in the metallic region, canted antiferromagnetic and ferromagnetic states coexist. Phase separation is suggested. (C) 2000 American Institute of Physics. [S0021-8979(00)41708-1].