Heuristic model for slow relaxation of excess conductance in electron glasses

We discuss relaxation of excess conductance Delta G observed in recent experiments on electron glasses. Using a simple model based on some salient features of a hopping system with interactions, we show that for relatively short times Delta G scales like ln(t) and it becomes faster than that as time evolves. The crossover to a faster than In(t) dependence occurs when w(min)t approximate to 1, where w(min) is the smallest relaxation rate in the system, and t is the observation time.