Hall effect study of magnetoresistive perovskite LaNi0.5Co0.5O3 thin films

We report on the Hall effect of LaNi0.5Co0.5O3 magnetoresistive thin films grown on Si(1 0 0) substrates by pulsed laser deposition. The Hall resistivity exhibits sign reversals both in varying magnetic field and temperature, which are indicative of a two-carrier type based conduction mechanism. Analysis of the Hall data in the framework of Chamber’s two-band conduction model suggests that the low-temperature magnetoresistance most likely arises from an electron mobility enhancement effect. Furthermore, ligand–holes seem to be responsible for the stabilization of the strong ferromagnetic interactions present in the compound. To our knowledge, this is the only other experimental observation, besides X-ray absorption experiments, consistent with ligand–hole ferromagnetism in cobaltites.