Abstract
We have measured the thermopower S and electrical conductivity sigma in a series of Cu-x(SiO2)(1-x) nanogranular films between 2 and 300 K with Cu volume fraction x varying from 0.43 up to 1.0. At low temperatures, disorder-enhanced electron-electron interaction effects dictate the behavior of sigma. A crossover of the temperature dependence from sigmaproportional to rootT to sigmaproportional toT(1/3) is observed as x is lowered and the metal-insulator transition is approached. S is small, shows linear temperature dependence, and is rather insensitive to the change of x. Effects of annealing are also discussed. (C) 2002 American Institute of Physics.