  A method for calculation of the magnetoimpedance in composite wires having an
insulator layer between non-magnetic core and soft magnetic shell is described.
It is assumed that the magnetic shell has a helical anisotropy and the driving
current flows through the core only. The distribution of eddy currents and
expressions for the impedance are found by means of a solution of Maxwell
equations taking into account the magnetization dynamics within the shell
governed by the Landau-Lifshitz equation. The effect of the insulator layer on
the magnetoimpedance is analyzed.
