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6.6.3 Domain Walls
Since the interaction of domain walls with defects affects the behaviour of magnetic materials, we now will see what the structure of a domain wall is.
A domain wall is often called as a Bloch wall, termed after F. Bloch who, in 1932, proved that magnetization cannot change discontinuously at a domain boundary. A Bloch wall defines a region between two neighbouring domains where the spin moments change gradually from one orientation to another, as shown below in case of 180° or antiparallel domains.
Bloch walls can be 10–100nm in width and can have energy of the order of 1*10-4 to 10*10-4 j.m-2.
| Figure 6.14 Domain wall structure in a ferromagnetic material |
As we wrote above, since favourably oriented domains grow at the expense of unfavourably oriented domains, the Bloch wall also moves towards the left, for the configuration shown above.
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