The giant-magneto-impedance effect in FM/Ag/FM (FM FeCuCrVSiB) samdwich films

Sandwich aims with the structure FM/Ag/FM have been prepared by radio-frequency sputtering and then annealed at an optimized temperature (here FM represents the FeCuCrVSiB amorphous soft magnetic layer). The giant-magneto-impedance (GMI) effects for the samples have been studied as a function of alternating-current frequency (50 kHz to 13 MHz) and external magnetic field. When the frequency increases above a critical frequency f* (about 150 kHz), the GMI ratio increases quickly with increasing frequency, and reaches a maximum value at a characteristic frequency f(m) of about 4 MHz. GMI ratios at f(m) as large as 109% and 135% were obtained for longitudinal and transverse applied magnetic fields, respectively. These results are much better than those obtained for single-layer films, and the frequencies used in producing the effect are very low.