Metal-insulator transition in disordered electron systems in two dimensions

We present a theory of the metal-insulator transition in a disordered two-dimensional electron gas. A quantum critical point is identified separating the metallic phase stabilized by electron interactions, from the insulating phase where the interactions are suppressed and disorder predominates. The quantum critical point leads to critical behavior in the thermodynamic properties due to the divergence of the density of states of the underlying collective modes at the transition. This mechanism, which is not related to the existence of any magnetic instability, explains the anomalous enhancement of the spin susceptibility observed near the metal-insulator transition.