Room-temperature coercivity enhancement in mechanically alloyed antiferromagnetic-ferromagnetic powders

The coercivity, $H_C,$ and squareness of Co powders have been enhanced at room temperature by mechanically alloying them with antiferromagnetic powders with Néel temperature, $T_N,$ above room temperature. The enhancement is maximum after field annealing above $T_N.$ The existence of loop shifts and the dependence of $H_C$ on the annealing and measuring temperatures indicate that exchange bias effects are responsible for this behavior.