Magnetostriction is a change of a material's shape or dimensions associated with its magnetization. A magnetic field can therefore produce strain without a contact force. The resulting magnetoelastic coupling lets a ferromagnet convert changes of magnetic state into mechanical motion; a constraint can instead turn the preferred deformation into stress. James Prescott Joule published his study of iron and steel bars in 1847.[ref]
The surprising point is that reversing the magnetization need not reverse the deformation. A material can prefer a longer axis along either or : an axis has no arrow. Isotropic linear magnetostriction vanishes excludes one particular linear constitutive term, while saturated isotropic magnetostrictive strain supplies a nonzero response with a quadratic dependence on the magnetic direction. The pulsed-field optical magnetostriction experiment shows how an actual length change can be resolved, and quadratic magnetostriction and frequency doubling separates an illustrative response law from a measured material curve.
Magnetostriction is a phenomenon in which a material changes its shape or dimensions in response to an applied magnetic field. This effect occurs in ferromagnetic and ferrimagnetic materials, where the arrangement of magnetic moments (magnetization) affects the lattice structure of the material. Essentially, as the magnetic domains within the material align in the presence of a magnetic field, the resulting changes in magnetization can lead to a mechanical strain.
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