  The magnetic, transport, and thermal properties of single crystals of the
series Fe(Ga1-xGex)3 are reported. Pure FeGa3 is a nonmagnetic semiconductor,
that when doped with small concentrations of Ge (extrinsic electrons), passes
through an insulator-to-metal transition and displays non-Fermi liquid (NFL)
behavior. Moreover, we observer clear signatures of a ferromagnetic quantum
critical point (FM-QCP) in this system at x = 0.052. The mechanism of the local
moment formation is consistent with a one-electron reduction of Fe dimer
singlets, a unique structural feature in FeGa3, where the density of these
mixed valence (Fe(III)-Fe(II)) dimers provides a unique tuning parameter of
quantum criticality.
