Abstract
Magnetization reversal in a SmCo3.5Cu1.5 single crystal has been observed as a functon of the field sweep rate in the range 10−5–104 Oe/sec. The reciprocal coercive force varies linearly with the logarithm sweep rate over a wide range, but lowers abruptly above a certain sweep rate. This seems to suggest that the rate controlling process of magnetization reversal changes from elementary nucleations on the parent domain walls to the domain growth resulting from wall migration.