Coherently photo-induced ferromagnetism in diluted magnetic semiconductors

Ferromagnetism is predicted in undoped diluted magnetic semiconductors illuminated by intense sub-bandgap laser radiation . The mechanism for photo-induced ferromagnetism is coherence between conduction and valence bands induced by the light which leads to an optical exchange interaction. The ferromagnetic critical temperature T_C depends both on the properties of the material and on the frequency and intensity of the laser and could be above 1 K.Comment: 11 pages, 2 figures, preprint styl