Giant magneto-impedance and surface hysteresis loops in Co-rich amorphous microwires

Abstract

Summary form only given. The giant magneto-impedance effect, GMI, became a topic of great interest owing to the large sensitivity (up to 300% in conventional amorphous wires) of the electrical impedance with the applied DC field. Generally lower GM I ratio has been observed for the other soft magnetic materials, In this paper we report on the observation of high GMI effect in glass coated amorphous microwires. Soft magnetic glass-coated Co/sub 67/Fe/sub 3.85/Ni/sub 1.45/B/sub 11.5/Si/sub 14.5/Mo/sub 17/ microwires with different geometric ratio, /spl rho/, of metallic nucleus diameter, d, to total microwire diameter, D, 0.78/spl les//spl rho//spl les/0.98 and low magnetic anisotropy field (50-200 A/m) has been fabricated. Dependencies of the magneto-impedance ratio, /spl Delta/Z/Z=[Z(H)-Z (H/sub max/)]/Z (H/sub max/), on axial, H/sub a/, and circular, H/sub c/, magnetic field has been investigated for the frequency, f, range 0.06-15 MHz, driving current amplitude, I, of 0.75-2 mA and H/sub a/ up to 2550 A/m. Conventional and surface (axial and circular) hysteresis loop have been measured by conventional induction method and longitudinal and transverse magneto-optical Kerr effect (MOKE).