  This work reports on structural and magnetic investigations of the Heusler
compound Co$_2$FeSi. X-Ray diffraction and M\"o\ss bauer spectrometry indicate
an ordered $L2_1$ structure. Magnetic measurements by means of X-ray magnetic
circular dichroism and magnetometry revealed that this compound is, currently,
the material with the highest magnetic moment ($6 \mu_B$) and Curie-temperature
(1100K) in the classes of Heusler compounds as well as half-metallic
ferromagnets.
