The giant magnetoimpedance effect in composite wires consising of anon-magnetic inner core and soft magnetic shell is studied theoretically. It isassumed that the magnetic shell has a helical anisotropy. The current and fielddistributions in the composite wire are found by means of a simultaneoussolution of Maxwell equations and the Landau-Lifshitz equation. The expressionsfor the diagonal and off-diagonal impedance are obtained for low and highfrequencies. The dependences of the impedance on the anisotropy axis angle andthe shell thickness are analyzed. Maximum field sensitivity is shown tocorrespond to the case of the circular anisotropy in the magnetic shell. It isdemonstrated that the optimum shell thickness to obtain maximum impedance ratiois equal to the effective skin depth in the mahnetic material.
展开▼
