Investigation of giant magneto-impedance effect in electroless-deposited CoP/Insulator/BeCu wires

By controlling the process conditions the CoP/Insulator/BeCu composite wires with distinct giant magneto-impedance effect (GMI) have been prepared by electroless-deposition on polyester-coated BeCu wires. The as-deposited sample was treated with current annealing. A dramatic increase of the GMI value was observed at a low frequency after current annealing. The maximum GMI ratio reaches about 991% and the field sensitivity a-mounts to 2.78%/(A·m^-1) at 97 kHz, The GMI value is above 50 K at the frequency range from 3 kHz to 30 MHz. The properties of magnetization processes for the annealed samples are analyzed via the complex permeability. The real and imaginary part of the complex permeability change significantly with the variation of DC magnetic field after current annealing.