Heusler alloys containing Co and Mn are amongst the most heavily studied
half-metallic ferromagnets for future applications in spintronics. Using
state-of-the-art electronic structure calculations, we investigate the effect
of doping and disorder on their electronic and magnetic properties. Small
degrees of doping by substituting Fe or Cr for Mn scarcely affect the
half-metallicity. A similar effect is also achieved by mixing the sublattices
occupied by the Mn and sp atoms. Thus the half-metallicity is a robust property
of these alloys