Annealed Local Magnetic Moments and the Metal-Insulator Transition in Disordered Electronic Systems

Local magnetic moments are generically self-generated in quenched disordered electronic systems. They can be described in terms of annealed magnetic disorder, i.e., magnetic disorder which is in equilibrium with the rest of the system. Incorporating this annealed magnetic disorder into a transport theory leads to a new mechanism and a new universality class for a metal-insulator transition. The transition is not driven by localization effects but by a vanishing thermodynamic density susceptibility. It thus resembles a Mott-Hubbard transition rather than an Anderson transition. We determine the critical behavior in d = 2 + ε dimensions and discuss the underlying physics.