Magnetostriction

Local stress may also be generated by the magnetostriction of the ferromagnetic material itself. Stresses only arise if the magnetostrictive strains are frustrated. The corresponding strain energy is

Here pe is the deviation from the nonmagnetostrictive state, ∈ is the strain in the freely deformed state and c is the tensor of elastic constants. c · ( pe − ∈) is the magnetostrictive stress σ. Thankfully this term is usually small, < 1 kJ m⁻³.