Extraordinary Hall effect in

The Hall effect of La0.7Ba0.3MnO3 and La0.7Ca0.3MnO3 thin films was measured in magnetic fields $\mu_0 H \leq 1$ T and for temperatures 10 K $\leq T \leq$ 340 K. In the ferromagnetic phase the slope of the Hall resistivity at zero magnetic induction rapidly increases with temperature until a maximum is reached at the Curie temperature TC. A detailed comparison of the Hall resistivity with the magnetization facilitates the separation of the ordinary and extraordinary Hall effect. The ordinary Hall constant RH shows a jump below TC. The extraordinary Hall constant RA scales with the zero-field resistivity. At low temperatures we find a quadratic dependence of RA on the resistivity crossing over to a linear dependence at higher temperatures. Whereas the quadratic scaling law in the ferromagnetic phase can be explained by a conventional side-jump mechanism, the linear dependence near TC and in the hopping regime is inconsistent with conventional skew scattering. The data are compared to a recent theory of the Hall effect in double-exchange ferromagnets