CONDUCTIVITY AND MAGNETOCONDUCTIVITY OF AMORPHOUS CRXGE1-X NEAR THE METAL-INSULATOR-TRANSITION

The electrical conductivity of amorphous CrxGel-x thin films has been investigated om the metallic side of the metal-insulator transition (M IT) between 50mK and 300K and below 4.2K in magnetic fields up to 8T. The results are discussed in terms of electron interaction and weak lo calization theories. Below 1K the conductivity is correlated with the width of the Coulomb gap in the density of states. The critical expone nt upsilon was found to be upsilon=(1.7+/-0.3). Far from the MIT the m agnetoconductivity (MC) is negative and can be qualitatively explained . In samples near the MIT a positive MC was observed below 1K, which i s linear in B for small fields and increases with decreasing temperatu re and increasing closeness to the MIT. These results are not yet unde rstood.