Theory of giant magneto-impedance in the planar conductor with uniaxial magnetic anisotropy

An electrodynamic theory of GMT,based on a simultaneous solution of linearized Maxwell's equations and Landau-Lifshitz equation of motion is presented. An analytical solution is found for the case of uniformly magnetized planar film with uniaxial in-plane magnetic anisotropy. The exchange-conductivity effect and two types of magnetic relaxation in the equation of motion are considered. The AC current is generally transmitted by four pairs of plane waves of mixed electromagnetic and spin-wave character. An analytical formula for the tensor of complex impedance is derived and is used for numerical calculations of longitudinal GMI effect. The influence of various material parameters on the magnitude and frequency dependence of GMI is discussed. (C) 1999 Elsevier Science B.V. All rights reserved.