Frequency dependence of GMI effect in nanocrystalline Fe 86Zr 7B 6Cu 1 ribbons

Abstract

Giant magnetoimpedance effect (GMI), Δ Z/ Z, has been studied in Fe 86Zr 7B 6Cu 1 ribbons after heat treatment at 550°C and 600°C for 1 h (samples A and B respectively). Measurements were performed at frequencies, f, of the AC driving current ranging between 50 and 1400 kHz and under an axial magnetic field, H, up to 1440 A/m. Increasing the frequency results in the appearance of a maximum on axial field dependencies of the total magnetoimpedence, Z, and its change, Δ Z/ Z. Besides, both samples showed frequency dependence of maximum Δ Z/ Z ratio, Δ Z/ Z m. Δ Z/ Z m has a maximum at 300 kHz for sample A when Δ Z/ Z m=12.5% and at 200 kHz for sample B when Δ Z/ Z m reaches 17.5%. Observed dependencies were interpreted in the classical way, taking into account the change of the penetration skin depth of the AC driving current in a magnetic conductor with high circular magnetic permeability.