A technique has been developed for the direct observation of magnetic domain‐wall motion in grain‐oriented silicon steel. The magneto‐optical Kerr effect was employed to obtain a visible contrast between antiparallel domains. Domain‐wall motion at 30, 60, and 120 cps was photographed using a high‐speed camera synchronized with a high‐intensity electronic‐flash system. Motion pictures at rates up to 5500 frames/sec were obtained. The effects of peak induction, waveform and frequency on domain‐wall motion were observed. The films showed that domain‐wall positions did not repeat precisely from cycle to cycle, particularly at high inductions, and that the average domain‐wall spacing decreased with increasing frequency. Frame‐by‐frame analyses of these high‐speed films revealed that domain walls may hang up, or become pinned several times during a reversal, and that a domain wall does not necessarily move as an entity. The pinning effects are attributed to the presence of non‐magnetic inclusions and/or surface...
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