Search for Nagaoka ferromagnetism in non-magnetic doped semiconductors

While ferromagnetism at relatively high temperatures is seen in diluted magnetic semiconductors such as Ga_{1 - x} Mn_x As, under certain conditions semiconductors doped with non-magnetic impurities may also exhibit a ferromagnetic ground state. We investigate the possibility of ferromagnetism in a generalized disordered Hubbard model designed to characterize hydrogenic centers in semiconductors. We demonstrate the occurrence of high spin ground states in clusters (e.g. doped quantum dots), and discuss the nature of the single-particle states in a positionally disordered three-dimensional system with a maximally spin-polarized ground state. In particular, we identify the mobility edges, and describe their dependence on impurity density and potential.