A series of studies on diluted magnetic semiconductors and on related compounds is a continuation of our activity from previous years. The results presented here were produced during the PhD thesis of Waly Ndiaye (2013). While semiconducting materials, where the transport of the charge can be controlled, are at the heart of electronics, ferromagnetic materials, with an imbalance in the number of spin-up and spin-down occupied electron states, are at the heart of magnetism. The combination of these two aspects in a single material, a magnetic semiconductor, should permit an electric control of spin transport. Such magnetic semiconductors should ideally have a Curie temperature above ambient temperature and a highly spin polarized current. In addition, for practical aspects, they should be compatible with the mainstream Si-based technology. For these reasons we have studied the Mn-Ge system. We studied Mn5Ge3(001) thin films grown on Ge(111) by angle- and spin-resolved photoemission using synchrotron radiation. The photoelectron spectra were simulated starting from a first-principles band-structure calculation for the ground state, using the free-electron approximation for the final states, taking into account photohole lifetime effects and k⊥ broadening plus correlation effects, but ignoring transition matrix elements. The measured spin polarizations for the various k points investigated in the Brillouin zone are found to be in fair enough agreement with the simulated ones, providing a strong support to ground-state band-structure calculations. [W. Ndiaye et al. PRB 2013 and 2015] back