Observation of giant Hall effect in granular magnetic films

The Hall effect in granular co-sputtered ferromagnetic metal-insulator films was found to increase dramatically as the magnetic volume fraction decreases toward the metal-insulator transition. The saturated Hall resistivity is up to 160 mu Omega cm at T=5 K, that is almost four orders of magnitude greater than that in a pure magnetic metal sample. Close to the metal-insulator transition, both magnetoresistivity and the saturated Hall resistivity decrease with increasing temperature. Correlations of the Hall resistivity with resistivity and magnetoresistivity are discussed. (C) 1996 American Institute of Physics