Giant magnetoimpedance in composite wires with insulator layer between   non-magnetic core and soft magnetic shell
  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. 
N.A. Buznikov, A.S. Antonov, A.B. Granovsky, C.G. Kim, C.O. Kim, X.P.   Li, S.S. Yoon