A new diluted magnetic semiconductor: The half-metallic ferromagnet CoTi_1-xFe_xSb

C1(b) compounds with 18 valence electrons are semiconducting. It will be shown that doping with electrons results in half-metallic ferromagnets, similar to the case of diluted semiconductors. CoTiSb is known to be a semiconducting C1(b) compound. Doping by Fe is expected to result in ferromagnetic order. It was found that Ti can be replaced by up to about 10% Fe while its crystal structure still remains C1(b), which was proved by x-ray powder diffraction. Superconducting quantum interference device magnetometry revealed a magnetic moment of 0.32 mu(B)/unit cell at 5 K