Coulomb tunneling anomaly in disordered copper-germanium alloys

We have performed electronic tunneling density of states and resistivity me asurements in three-dimensional CuxGe100-x films spanning the weakly and st rongly localized regimes. We found that the Coulomb anomaly in tunneling de nsity of states in the strongly disordered regime is very profound and grow s in strength with resistivity. However, when the system becomes less disor derly and approaches the weakly disordered regime, this anomaly weakens rap idly. The data suggest that the disorder enhanced electron-electron interac tion effects can drive the crossover from weak: disorder to strong disorder in CuGe alloy system. (C) 2000 Elsevier Science B.V. All rights reserved.