This study of amorphous Gd‐Mn, Y‐Mn and their ternary alloys with Co prepared as films by co‐evaporation indicates that, (a) the Mn moment is compositionally dependent going from ?2&mgr;Bto 0.5&mgr;Bper Mn with increased Mn concentration in the alloy, (b) Gd‐Mn and Gd‐ (CoMn) order with antiparallel Gd and Mn moments or (CoMn) moments while Y‐Mn samples remain paramagnetic, (c) Curie temperatures are relatively constant with composition which we have interpreted in terms of the Mn‐Mn exchange interaction, and (d) the spontaneous Hall effect for Mn as given by &rgr;H/&rgr; (Hall resistivity/sample resistivity) is about −0.01 per &mgr;Bof Mn which is opposite in sign to Fe or Co.