What is bloch wall energy?

Answer 1

180o domain wall between two domains is known as Bloch wall. The Bloch wall energy is competition between exchange energy and anisotropy energy within the interface of two domains. The exchange energy in a ferromagnetic material is a minimum only when adjacent spins are parallel. While anisotropy energy will be minimum when the spins remain parallel to the easy axis.

Bloch wall energy will be minimum of exchange energy and anisotropy energy

Mathematically, the Bloch wall energy for an uniaxial anisotropic material will be

(sigma)exch+(sigma)anis=(JS2 pi2)/Na2+KuNa

where J is exchange stiffness, N is number of atoms within the wall, a is distance between two adjacent atoms, Ku is the uniaxial anisotropy constant

the minimum of this energy terms will be

(sigma)dw~2pi(AKu)1/2

where A is the exchange stiffness constant. it is the energy of the Bloch wall in uniaxial ferromagnetic material. (read more in Cullity's Book)

Answer 2

Bloch wall energy is the energy associated with the creation of a domain wall in a magnetic material. It represents the energy required to change the orientation of magnetic domains within the material. Bloch walls are important in understanding magnetic domain structures in ferromagnetic materials.