Lattice Distortion, Polaron Conduction, and Jahn-Teller Effect on teh Magnetoresistance of La(sub 0.7)Ca(sub 0.5)CoO(sub 3) Epitaxial Films

In summary, we have investigated the role of lattice distortion, polaron conduction and Jahn-Teller coupling in the occurrence of the colossal negative magnetoresistance in perovskite oxides. We conclude that larger lattice distortion gives rise to larger zero-field resistivity and larger magnitude of negative magnetoresistance.