Magnetic characteristics of epitaxial Ge(Mn,Fe) diluted films -a new room temperature magnetic semiconductor?

We prepare 100 nm thick, epitaxial Ge100-(x+y)(Mnx,Fey) diluted films with Mn and Fe concentrations of several at% using a layer-by-layer deposition scheme at elevated temperature. We measure saturation magnetization mS versus temperature curves for a variety of (x,y) combinations and find for fixed temperatures a non-trivial dependence of mS on x and y. Within a certain window in the (x,y) parameter space Ge100-(x+y)(Mnx,Fey) exhibits a Curie temperature of 350 K and mS≈ 10 emu/cm2 at room temperature.