Effect of fiber laser treating on magnetic domains in the grain-oriented silicon steel: Imaging domains by bitter, MFM and kerr microscopy

Abstract

A magnetic domain laser scribing technique of grain-oriented 3.2% silicon steel has been investigated for the direct influencing on the magnetic domain wall. The magneto-optical Kerr effect was employed to obtain a visible contrast between antiparallel domains. The effects of laser treating on domain wall were observed. The Bitter, MFM and Kerr microscope pictures 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 density of laser scribing lines. Two phenomena have been discovered that are difficult to explain (1) that the hardness decreases with increasing laser energy and (2) that the coercivity decreases with decreasing laser energy. A semi-quantitative relationship has been found between the domain patterns and used fiber laser treating method. The behavior of patterns in an applied magnetic field is shown, and based on that a two-dimensional laser lines configuration is proposed for one of the less complicated surface patterns.