MAGNETIZATION REVERSAL AND DOMAIN-WALL MOTION IN THIN NI WIRES

We have studied magnetization reversal in small diameter Ni wires. Thi s process appears to be dominated by the pinning of domain walls on de fects. At high temperatures (T > 2 K) motion past pinning sites seems to occur via thermal activation over the associated potential barrier. There is some evidence that macroscopic quantum tunneling becomes imp ortant at lower temperatures.