Hopping conductivity in granular disordered systems

摘要: We study the temperature dependence of conductivity for high-resistivity granular disordered systems in terms critical-path method. It is shown that low-field $\mathrm{exp}(\ensuremath{-}\frac{A}{{T}^{\ensuremath{\alpha}}})$ with $\ensuremath{\alpha}=\frac{1}{2}$ obeyed over large ranges possible crossovers to $\ensuremath{\alpha}=\frac{1}{4}$ at low temperatures and $\ensuremath{\alpha}g\frac{1}{2}$ high temperatures. The which occur depend on distribution grain sizes. Comparisons are made experiments other theoretical approaches.