Itinerant Ferromagnetism in Disordered Metals: A Mean-Field Theory

We develop a mean-field approach to interacting disordered systems of itinerant electrons based on a statistical treatment of disorder enhanced Hartree-Fock interactions. We demonstrate that for $d\le 2$ a disordered system may exhibit a finite temperature partial spin polarization even if its clean analog is paramagnetic. The disorder and temperature dependent magnetization and spin susceptibility are calculated. Possible relevance to recent experiments on quantum dots is discussed.