TRANSPORT-MAGNETISM CORRELATIONS IN THE FERROMAGNETIC OXIDE LA0.7CA0.3MNO3

We present results of temperature and magnetic field dependent resistivity rho(H,T) and bulk magnetization M(H,T) measurements on post-annealed La0.7Ca0.3MnO3 thin films that were grown via pulsed-laser deposition. Both the resistivity and the anomalously large negative magnetoresistance peak near the ferromagnetic ordering temperature (T-c=250 K), with Delta rho/rho(0)=-85% at 50 kOe. A clear correlation is found between rho and M that is described by the phenomenological expression rho(H,T)(proportional to)exp[-M(H,T)/M(0)]. This correlation reflects the important interplay between transport and magnetism in this system, and suggests that the transport below T-c involves polaron hopping. (C) 1995 American Institute of Physics.