Reversal mechanism in copper-modified cobalt-rare-earths

The magnetization reversal in copper-containing cobalt-rare-earth permanent magnet materials can be completely dominated by pure bulk wall-pinning. This is shown by the form of hysteresis loops in varying magnetizing fields, whose appearance is in extreme contrast to those of unmodified cobalt-rare earths, in which nucleation is the dominant factor in magnetization reversal. In some copper-modified materials it is possible to show both kinds of behavior in the same sample, with a sudden transition at a particular value of magnetizing field.