I. Quantum Phase Transitions

  1. Metal-Insulator Transitions
  2. Ferromagnetic Transitions

II. A Model for Interacting Disordered Electrons

  1. Generalized Nonlinear Sigma-Model
  2. Universality Classes
  3. Metal-Insulator Transitions

III. Ferromagnetic Transition in the Generic Universality Class

  1. Low-Order RG
  2. Perturbation Theory to All Orders
  3. Ferromagnetic Transition
  4. Order Parameter Theory
  5. Confirmation by Other Approaches
  6. Metal-Insulator Transition

IV. Summary and Conclusion

Magnetic Properties of Disordered
Interacting Electrons *


D. Belitz+
University of Oregon

Abstract: The magnetic properties of disordered interacting electron systems are discussed. It is shown that the runaway flow in d>2 that has given rise to confusion in the past is an artifact of a one-loop approximation. The perturbation theory can be controlled and resummed to all orders, and for small disorder near d=2 a ferromagnetic transition emerges. This has been confirmed by an explicit order parameter theory for the magnetic transition.


* With T.R. Kirkpatrick, M.T. Mercaldo, S.L. Sessions
+ belitz@greatwhite.uoregon.edu



I. QUANTUM PHASE TRANSITIONS


Quantum phase transitions occur at T=0 as a function of some non-thermal control parameter.

Most obvious examples in disordered interacting electron systems:





II. A MODEL FOR INTERACTING DISORDERED ELECTRONS


1. Generalized Nonlinear Sigma Model



2. Universality Classes



3. Metal-Insulator Transitions in Systems with Spin-Flip Mechanisms