Half-metallic ferromagnetism with high magnetic moment and high Curie   temperature in Co$_2$FeSi
  Co$_2$FeSi crystallizes in the ordered L2$_1$ structure as proved by X-ray diffraction and M\"o\ss bauer spectroscopy. The magnetic moment of Co$_2$FeSi was measured to be about $6\mu_B$ at 5K. Magnetic circular dichroism spectra excited by soft X-rays (XMCD) were taken to determine the element specific magnetic moments of Co and Fe. The Curie temperature was measured with different methods to be ($1100\pm20$)K. Co$_2$FeSi was found to be the Heusler compound as well as the half-metallic ferromagnet with the highest magnetic moment and Curie temperature. 
Sabine Wurmehl, Gerhard H. Fecher, Vadim Ksenofontov, Frederick   Casper, Ullrich Stumm, Claudia Felser, and Hong-Ji Lin