Abstract
A saw-tooth domain pattern has been observed in a (001) Fe-3%Si single crystal using the magneto-optic Kerr effect by applying gradient field, and a charged wall has been investigated. A domain bounded by a straight 180° Bloch wall changes into a saw-tooth domain separated by a zig-zag charged wall with the gradient of field. The relation between the charged wall energy and the effective field gradient is obtained by considering the wall and the field energies in the gradient field.
A model of the charged wall is proposed to combine the 180° Bloch-like and Néel-like regions. The variation method is applied to the free energy of the Néel-like regions to obtain the minimum free energy, the configuration of magnetization and the distribution of pole density in these regions. Furthermore, by considering the wall energy of the inclining 180° Bloch wall to the minimum free energy of the Néel-like regions, the wall energy γ(θ) of the charged wall of tilt angle θ is obtained as follows:
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oindentThe estimated energy of the charged wall in the range |θ|≤12° is smaller than the maximum energy of the inclining 180° Bloch wall.
