Magnetic amorphous Co-Cd powders prepared by mechanical alloying

Amorphous Co1-xGdx powders with x = 0.10, 0.15, 0.20 and 0.25 were prepared by mechanically alloying mixtures of elemental cobalt and gadolinium powders in a laboratory high-energy ball mill. The alloys crystallize above 500°C. The magnetic properties of the amorphous powders were measured in toroidal samples made by cold pressing the powders. For x ⩽ 0.15, amorphous Co-Gd is ferromagnetic at all temperatures. In amorphous Co75 Gd25, the net magnetic moment has a minimum near the compensation temperature Tcom = 50°C, at which the cobalt and gadolinium spins align in opposite directions. The low-temperature magnetic moment of this alloy suggests that, on cooling, it forms a spin glass with a freezing temperature of 60K.