Materials with large magnetostrains

Abstract

A review is given of the basic concepts which underlie the magnetostrictive behavior of ferromagnetic materials. The microscopic, i.e., atomic and electronic properties of magnetoelastic ferromagnets are discussed, with an emphasis on anisotropic magnetostriction. The latter is defined as the change in dimension of a ferro-magnet caused by rotation of the magnetization. Formulae for length changes along a given direction in terms of the magnetization direction are derived for cubic and hexagonal crystals. Approximations for the saturation strain of polycrystalline aggregates are discussed and compared with data on cubic crystals. Results of saturation magnetostriction measurements of rare-earth compounds and alloys are reviewed and tabulated. Finally, a brief discussion is given of the relationship between lattice structure and magnetostriction.