This patent document describes a novel class of ferromagnetic semiconductors with compositions of (Ba,Sr)M2?Ru4?O11 (1 ≤ (x+y) ≤ 5; 0 ≤ z ≤ 1) and (Ba,Sr)M2?Ru4?O11 (M=Fe,Co). Single crystal and polycrystalline samples were synthesized and showed ferromagnetism and tunable semiconducting properties. These materials have potential applications in spin-based transistors, light emitting diodes, and magnetic random access memories.