Magnetostriction and magnetoelasticity

The physical concepts magnetostriction and magnetoelasticity are presented. Spontaneous volume magnetostriction and saturation linear magnetostriction are distinguished. Various magnetoelastic phenomena are introduced, but the emphasis is on magnetostriction in bulk samples and thin films. The equations for magnetostrictive and magnetoelastic coefficients are derived for cubic, hexagonal, and isotropic systems. Experiments on the measurement of the linear magnetostriction λi and magnetoelastic coupling coefficients Bj are discussed. Ab initio-based theory elucidates the physical origin of magnetostrictive effects in metals at the electronic level, although accurate calculations are often elusive. The magnetoelastic properties of nm thin films may deviate in magnitude and sign from the bulk values. Both experiment and theory identify substrate-induced lattice strain as a driving force for this deviation. Data on magnetostriction and magnetoelasticity are compiled, including those of highly magnetostrictive systems, such as (Tb,Dy)Fe2 (Terfenol) and (Fe,Ga) (Galfenol)