Magnetostriction. Animation shows a strip domain structure in a ribbon with an axis of easy magnetization perpendicular to the applied magnetic field H. Under the action of magnetic field the domains may rotate. This causes expansion of a sample.

If the axis of easy magnetization coincides with direction of applied field H, then magnetization occurs by means of domain walls motion. Thus, if the sample was magnetized to saturation, then reversal magnetization occurs sharply when magnetic field achieves anisotropy field Ha. The rectangular loop of a hysteresis is observed.

In a case when the axis of easy magnetization is perpendicular to the field H, magnetization occurs by rotation of domains. In this case the linear loop of a hysteresis is observed.

Two adjacent domains magnetized in opposite directions are always  separated by a transitive layer (Bloch Wall) in which there is a gradual turn of spins as shown in animation. Magnetization is accompanied with a movement of such Bloch Wall.

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