Formation of asymmetric giant magnetoimpedance in amorphous ferromagnetic wires by micro magnets

Asymmetric giant magnetoimpedance (AGMI) was created using two micro magnets placed at 1 cm away from the ends of amorphous ferromagnetic non-magnetostrictive (Fe_0.06Co_0.94)_72.5Si_12.5B₁₅ wire. At low frequencies, single-peak behaviour of the AGMI was observed, and the AGMI curves exhibited two-peak behaviour within high-frequency range. The asymmetry in the magnetization curves of amorphous wire with two micro magnets having the same orientation was found, the maximum of the GMI ratio at positive field region decreases from 515% to 356%, and the peak value at negative field region decreases from 513% to 261% at 1 MHz driving current frequency. A linear change in the AGMI curves was obtained, which could be of importance for magnetic sensor applications. Experimental results were qualitatively explained in the framework of a model for the AGMI response in amorphous wire taking into account effects of bias field induced by micro magnets. (paper)