Magnetic properties of disordered systems near a metal-insulator transition.

Using doped semiconductors as a paradigm, the magnetic behavior of a disordered system undergoing a metal-insulator transition is described and contrasted with the situation in the absence of disorder. After a brief review of the insulating phase, the region in the vicinity of the transition is described. Low temperature magnetic and thermodynamic data of phosphorus doped silicon are compared with results from the perturbative scaling approach for weakly disordered systems with electron interactions, as well as a phenomenological model motivated by scaling studies of the highly disordered Hubbard model.