Giant Hall effect in nonmagnetic granular metal films

Nearly 3 orders of magnitude enhancement in the Hall coefficient is observe d in Cu-x -(SiO2)(1-x) granular films. This large enhancement of the Hall c oefficient not only is significantly larger than the prediction of the clas sical percolation theory, but also occurs at a metal concentration identifi ed to be the quantum percolation threshold. Measurements of the electron de phasing length and magnetoresistance, plus the TEM characterization of micr ostructures, yield a physical picture consistent with the mechanism of the local quantum interference effect.