Question

Why there is domain wall thickness (typical 40 nm) between magnetic domains for a typical ferromagnetic material? ( for ferroelectric materials, there is no thickness for the domain boundary)

Answer 1

Answer :-

* Domain wall split two domains where in magnetic dipoles points in different direction.

* The exchange interaction which creates the magnetization tends align nearby dipoles so that they point in same direction.

* facing adjacent dipoles to point in different direction require energy.

* Therefore, a domain wall requires extra energy which is proportional to area of the wall.

* So these are two energies are in picture.

* One is exchange energy which tries to increase width as much as possible.

* Other is anisotropic energy which makes the wall as this as possible.