Model calculations of torque-induced axial magnetization in circumferentially magnetized rings: Small angle approximation

We report calculations of the axial magnetization developed in a ferromagnetic, magnetostrictive ring initially magnetized in a circumferential direction and then subjected to a torque. The ring is assumed to consist of single-domain crystallites, and six specific cases are considered, corresponding to uniaxial, cubic {1 1 1}-easy, and cubic {1 0 0}-easy magnetocrystalline anisotropy with the crystallites either aligned circumferentially or distributed isotropically. Exact solution is possible only for the aligned uniaxial case; for the others, we employ the small-angle approximation in which the departure of each moment from its remanent-state easy direction in the presence of torque is taken to be small. We also extend our results to composites consisting of magnetostrictive material in a nonmagnetic matrix. (C) 1997 Elsevier Science B.V. All rights reserved.