Doped semiconductors, being a physical realization of an ensemble of one- electron (hydrogenic) atoms distributed randomly in space, are in a sense the simplest disordered system. Our current understanding of their magnetic properties is reviewed, for densities on both sides of a critical density nc at which the system undergoes a transition (at zero temperature) from an insulating phase (n < nc) to a metallic phase (n > nc). It is argued that the insulating phase is well modeled in terms of a disordered Heisenberg anti- ferromagnet, and quantitative agreement with experiment can be obtained. In contrast, the metallic phase just beyond nc, is not as well understood, and a number of possible candidate models are described. Finally, the issue of the effect of magnetic properties on the metal-insulator transition is addressed.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Mathematical Physics
- Condensed Matter Physics