Domain Transformation and MI of Melt-extracted Co_68.15Fe_4.35Si_12.25B_13.25Nb₁Cu₁ Microwires by Cryogenic Joule Annealing

Giant magneto-impedance (GMI) effect and domain transformation for melt-extracted Co_68.15Fe_4.35Si_12.25B_13.25Nb₁Cu₁ amorphous wires have been induced by a cryogenic Joule annealing (CJA) treatment with different DC current amplitude (0~350 mA) for 240s. Experimental results indicate that the maximum GMI ratio ([ΔΖ∕Ζ₀]_max) achieves to 188.1% with exciting field increasing to 1.8 Oe monotonically for 300 mA annealing treated wires, which can attribute to the surface complex domain structure change formed by CJA treatment. The liquid nitrogen can protect the wire from crystallization when applied large DC currents. Moreover, the CJA treatment can improve the response sensitivities effectively. These remarkable characteristics make the melt-extracted microwires by CJA tailoring as the promising candidate material for small-sized magnetic sensors.

Keywords:
melt-extracted microwires; cryogenic Joule annealing; giant magneto-impedance; domain transformation