GIANT HALL-EFFECT IN PERCOLATING FERROMAGNETIC GRANULAR METAL-INSULATOR FILMS

We studied both the resistivity and the Hall resistivity of cosputtere d granular Ni-SiO2 films with the metal volume fraction x in the range of 0.5-1.0. Near the metal-insulator transition, or x of about 0.53-0 .61, the saturated value of the Hall resistivity was up to 2 X 10(-4) Omega cm. This value is almost 4 orders of magnitude greater than that of pure nickel. Both the resistivity and the Hall resistivity varied weekly with temperature, throughout the range of 5-300 K. We suggest t hat the percolating ferromagnetic granular metal films can be an alter native candidate material for high sensitivity Hall sensors. (C) 1995 American Institute of Physics.