Percolation-type description of the metal-insulator transition in two dimensions

A simple noninteracting-electron model, combining local quantum tunneling a nd global classical percolation (due to a finite dephasing time at low temp eratures), is introduced to describe a metal-insulator transition in two di mensions. It is shown that many features of the experiments, such as the ex ponential dependence of the resistance on temperature in the metallic phase , the linens dependence of the exponent on density, the e(2)/h scale of the critical resistance, the quenching of the metallic phase by a parallel mag netic field, and the nonmonotonic dependence of the critical density on a p erpendicular magnetic held, can be explained by the model.