Carrier-induced ferromagnetism in Ge(Mn,Fe) magnetic semiconductor thin-film structures

We report on the carrier-induced ferromagnetism in Ge(Mn,Fe) magnetic semiconductor insulating-type thin-film structures prepared using sequential deposition at T-g=520 K with subsequent annealing at T-g. In the resulting films Mn and Fe are diffused in the Ge matrix without compromising the epitaxial structure. The anomalous Hall effect serves as a manifestation of the carrier-induced magnetism, with p-type conductivity and the Curie temperature T-C=209 K. The additional doping with Fe stabilizes epitaxial growth and carrier-mediated magnetism at levels of magnetic doping exceeding 10%. We conclude that indirect ferromagnetic exchange is mediated by localized holes with concentration n similar to 10(20) cm(-3) and mobility mu similar to 10 cm(2)/(V s). (c) 2006 American Institute of Physics