Magneto-impedance in NiFe/Au/NiFe sandwich films with different types of anisotropy

Various field behaviours of the magneto-impedance (MI) have been obtained using narrow NiFe/Au/NiFe sandwich films with the transverse, longitudinal and crossed anisotropies at the megahertz range. In the case of the transverse or longitudinal anisotropies, the MI response is always symmetrical with respect to the external DC field, whereas in the film with the crossed anisotropy it becomes asymmetrical in the presence of a bias current. Similar features of the MI behaviour have been reported before for ferromagnetic microwires with the circumferential (symmetrical MI) and helical (asymmetrical MI) anisotropies. The film with a longitudinal anisotropy exhibits a new type of field dependence, which differs from the transverse one in spite of its symmetry.