Giant Magneto-Impedance of Co₅₀Ni₂₂Ga₂₈ Alloy with High Chemical Ordering

The microstructure of Co₅₀Ni₂₂Ga₂₈ ribbon with the L₁₀ structure is examined. The band-like morphology is observed. These bands with the width in a range of 40--200nm appear along the transverse direction of the ribbon. The giant magnetoimpedance (GMI) effect in this alloy is measured. The results show that Co₅₀Ni₂₂Ga₂₈ exhibits a sharp peak of the GMI effect. The maximum GMI ratio up to 360% is detected. The GMI effect measured versus temperature shows large jumps of the magnetoimpedance amplitude at the reversal martensitic transformation temperature 240°C and Curie temperature 375°C respectively. The jump ratios of the magnetoimpedance amplitude examined at these temperatures are about 5 and 10, respectively.