A REEVALUATION OF MAGNETOCRYSTALLINE ANISOTROPY AND MAGNETOSTRICTION CONSTANTS

The standard theory of magnetocrystalline anisotropy for a rigid ferro magnetic body, with cubic symmetry, makes use of a ''zero strain'' ani sotropy constant K1. If the effect of magnetostriction is taken into a ccount, this constant must be replaced by a ''zero stress'' anisotropy constant K1', which differs from K1 by a term involving magnetostrict ion constants and elastic constants. There axe also zero strain and ze ro stress versions of higher order constants (K2, etc) for cubic symme try, as well as for other symmetries. The constant K1' also appears in dynamic behavior of ferromagnets driven by an applied field, unless t he field changes too rapidly for the system to remain in equilibrium. It is predicted that ferromagnetic resonance (FMR) experiments give a direct measurement of K1.