Magnetic Domains
Microscopic regions within a ferromagnetic material where atomic magnetic moments are aligned parallel in a uniform direction.
Governing formula
Domain Wall Energy E_total = E_exchange + E_anisotropy
SI unit
μm to mm (Domain Size)
In depth
Ferromagnetic materials divide into domains to minimize magnetostatic magnetostatic dipole energy. In an unmagnetized iron bar, domain orientations are random; external magnetic fields cause domain walls to shift and align.
Examples in the real world
Barkhausen noise pulses generated during magnetic domain wall movement in transformer iron cores.