The influence of surface conditions on the coercive force of SmCo5particles

The magnetic properties of single crystals of SmCo
5
have been studied. The spontaneous magnetization was 894 emu/cm
³
at room temperature. The process of magnetization reversal was extremely sensitive to the surface condition. The magnetization reversal process for spheres with rough surfaces was dominated by free wall motion, while the magnetization for spheres with the smoothest surfaces reversed by means of a jump from the completely magnetized state to the completely reversed state. These latter spheres had an energy product equal to the limiting value of
(BH)_{\max} = 31.6
MGOe. Some preliminary data for NdCo
5
and YCo
5
are also presented.