Ferromagnetism in Mn-doped Ge

We have successfully fabricated highly (up to 6%) Mn-doped bulk Ge single crystals. The lattice constant increases linearly with Mn concentration due to the larger Mn atomic radius compared with Ge, strongly indicating that Mn ions are being incorporated into the host Ge lattice. Alloys with lower Mn concentrations showed paramagnetism due to localized magnetic ions. ${\mathrm{Ge}}_{0.94}{\mathrm{Mn}}_{0.06}$ showed ferromagnetic ordering at ∼285 K, as determined from temperature-dependent magnetization and resistance measurements. The coersive field was 1260 Oe at 250 K.