Strong correlations between magnetic Barkhausen noise (MBN) and the motion of magnetic domain walls (DWs) have been confirmed by experiments. However, the developed MBN probe and the domain pattern observation system have a severe mismatch in time-domain sampling interval and spatial resolutions. This makes it difficult to identify the exact dependency of the DW velocity on the MBN amplitude. In this study, MBN imaging with spatial resolution in submillimeter scale and domain pattern observation with a frame rate of 14 480 fps are realized in an integrated system. Much experimental data are obtained at locations both near and far from the grain boundary in grain-oriented silicon steel. Careful examinations are performed using the fused data, and it is found that linear correlation is only adequate in the stage of magnetization reversal near the coercive field, while strong nonlinear correlation was reported in grain-oriented silicon steel under the near-zero-field reversal stage. The existing theoretical model is derived under a quasistatic magnetic field, and it cannot predict the experimentally observed nonlinear behavior. To solve this problem, an improved model is proposed that takes into account the hinder effect of a microscopic eddy current applied to the domain motion. An empirical formula is derived for predicting the nonlinear dependency of the DW velocity on the MBN amplitude, and its success is validated experimentally.

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• Domain walls
• Magnetism
• Magneto-optical Kerr effect
• Optically detected magnetic resonance