MAGNETOTRANSPORT AND HYSTERETIC BEHAVIOR IN EPITAXIAL LA0.67CA0.33MNO3-DELTA FILMS

We have fabricated epitaxial La0.67Ca0.33MnO3-delta thin films using p ulsed laser deposition and performed subsequent thermal treatments. Ma gnetoresistance values as large as 14000% (Delta rho/rho(H)) were obta ined. Above magnetic ordering temperatures, we observed a thermally ac tivated conductivity that also has a quadratic magnetic field dependen ce. At low temperatures, we found a large hysteresis in the magnetores istance that correlates with an unusual magnetic hysteresis curve. We interpret the hysteretic behavior as the result of a ''frozen-in'' can ted spin structure. Our results suggest that the electron conduction i n this material is most sensitive to the canting angle of the neighbor ing Mn spins. (C) 1996 American Institute of Physics.