Giant Hall effect in percolating ferromagnetic granular metal-insulator films

Abstract
We studied both the resistivity and the Hall resistivity of cosputtered granular Ni–SiO2films 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 2×10−4 Ω cm. This value is almost 4 orders of magnitude greater than that of pure nickel. Both the resistivity and the Hall resistivity varied weakly with temperature, throughout the range of 5–300 K. We suggest that the percolating ferromagnetic granular metal films can be an alternative candidate material for high sensitivity Hall sensors.