Fe3Si/GaAs(001) hybrid structures of high crystal and interfacial perfection are fabricated by molecular beam epitaxy at 200° C. The composition of the films can be tuned over a wide range of Si content. The Fe3Si/GaAs(001) films are robust against thermal annealing up to 425° C. Room-temperature spin injection is demonstrated from the ferromagnetic metal Fe3Si into the semiconductor GaAs by analyzing the circular polarization of the electroluminescence intensity emitted by an n-i-p light-emitting diode. © 2005 Elsevier B.V. All rights reserved.