Figure 12.
Phase diagram of the transport regimes of granular metals. In the insulating regime for g < gc thermally activated transport is observed of the Arrhenius type at elevated temperatures, which crosses over to correlated VRH due to inelastic or elastic cotunneling in the presence of potential disorder in the grains. In the metallic regime for g > gc a universal logarithmic correction for kBT > Γ is expected, which saturates at lower temperature as coherent transport develops (granular Fermi liquid). Adapted from [48].