Very low-temperature epitaxial growth of Mn₅Ge₃ and Mn₅Ge₃C_0.2 films on Ge(111) using molecular beam epitaxy

C-doped Mn₅Ge₃ compound is ferromagnetic at temperature up to 430 K. Hence it is a potential spin injector into group-IV semiconductors. Segregation and diffusion of Mn at the Mn₅Ge₃/Ge interface could severely hinder the efficiency of the spin injection. To avoid these two phenomena we investigate the growth of Mn₅Ge₃ and C-doped Mn₅Ge₃ films on Ge(111) substrates by molecular beam epitaxy at room-temperature. The reactive deposition epitaxy method is used to deposit these films. Reflection high energy electron diffraction, X-ray diffraction analysis, transmission electron microscopy and atomic force microscopy indicate that the crystalline quality is very high. Magnetic characterizations by superconducting quantum interference device and ferromagnetic resonance reinforce the structural analysis results on the thin film quality. - Highlights: • Epitaxial Mn₅Ge₃ and C-doped Mn₅Ge₃ films grown on Ge(111) at room temperature. • Mn₅Ge₃ and C-doped Mn₅Ge₃ films grown by reactive deposition epitaxy. • RHEED, XRD and TEM measurements show a very high crystallinity. • Magnetic measurements support the structural analysis in the crystalline quality. • Ferromagnetic resonance linewidth is very narrow (3.5 mT at RT)