Giant magneto-impedance effect of two paralleled amorphous microwires

Abstract

Giant magneto-impedance (GMI) is effectively enhanced by the mutual magnetic interaction between two amorphous microwires. A comparative study on GMI properties of a single wire and two wires arranged in parallel mode was reported in this work. Two-peak (TP) of impedance characteristic is presented when the dc external field changed from 0 to 320 A·m−1 in two-wire system, which is attributed to successive magnetization process in two wires induced by their magnetic interaction. And the evolution of single peak to TP phenomenon, when the distance between two wires is upto 8 mm, evidences a distance dependence of transformation from successive magnetization to simultaneous via a corresponding distance dependence of magnetostatic interactions. It is proposed that the recombination of magnetic interaction and the shielding effect results in a distance dependency of GMI response. When the distance is 8 mm, the magnetization process is close to synchronous between two wires, which give rises to higher circular permeability and better GMI response. The impedance ratio ΔZ/Z increases from 74.5 % of single wire to 172.4 % at 10 MHz. However, when the distance is upto 12 mm, the magnetic interaction is weak and magnetization process is completely independent, and GMI response decreases, relatively. This indicates that the GMI response could be effectively improved in a two-wire connection with an optical distance, which is promising and useful for the application of high-performance GMI sensors.