Resistivity and Hall effect at high temperatures in La0.67Ca0.33MnO3

The resistivity tensors of La0.67Ca0.33MnO3 films were investigated at temp eratures from the Curie temperature up to 600 K in magnetic fields up to 20 T. The diagonal transport is described by hopping of a small spin polaron cluster of 4 ions to nearest-neighbor spins. A spin-dependent activation en ergy and a mean field approximation for the magnetization of clustered pola ron spins and unclustered Mn ion spins allowed the description of rho(B, T) with a minimum of free parameters. The electron-like low field Hall coeffi cient showed a thermally activated behavior with an activation energy highe r than that extracted from diagonal data. (C) 1999 American Institute of Ph ysics. [S0021-8979(99)19408-8].