  Magneto-optical Kerr effect hysteresis loops at various wavelengths in the
visible/near-infrared range have been used to characterize the magnetic
properties of alloys obtained by implanting Mn ions at fixed energy in a Ge
matrix. The details of the hysteresis loops reveal the presence of multiple
magnetic contributions. They may be attributed to the inhomogeneous
distribution of the magnetic atoms and, in particular, to the known coexistence
of diluted Mn in the Ge matrix and metallic Mn-rich nanoparticles embedded in
it [Phys. Rev. B 73, 195207(2006)].
