Electron Transport in Granular Metals

The thermodynamic and transport properties of a long granular array with strongly connected grains (intergrain conductance g≫1) were studied. It was found that the system's conductance and differential capacitance exhibits activated behavior ∼ exp{-T^*/T}. The gap T ^*represents the energy needed to create a long single-electron charge soliton propagating through the array. It was shown that the inelastic tunneling and weak charge quantization lead to the insulating behavior at the temperature below T^*∼E_ce^-g/4.