Extraordinary Hall effect in and thin films

Department of Physics and Astronomy, University of Sheffield Sheffield S3 7RH, UK

Received: 9 June 1998
Accepted: 9 November 1998

Abstract

The Hall effect of La_0.7Ba_0.3MnO₃ and La_0.7Ca_0.3MnO₃ thin films was measured in magnetic fields  T and for temperatures 10 K 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 T_C. A detailed comparison of the Hall resistivity with the magnetization facilitates the separation of the ordinary and extraordinary Hall effect. The ordinary Hall constant R_H shows a jump below T_C. The extraordinary Hall constant R_A scales with the zero-field resistivity. At low temperatures we find a quadratic dependence of R_A 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 T_C 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.