Effect of Shape and Annealing on the Giant Magnetoimpendence Properties of FeCoSiB Ribbon

The annealing process and shape are expected to significantly affect the magnetic properties and giant magnetoimpedance (GMI) effect of magnetic amorphous ribbon. Here, the GMI effect in the annealed samples of FeCoSiB with different aspect ratios was studied at the frequency range between 1 and 40 MHz. Magnetic properties and microstructures of samples were investigated by vibrating sample magnetometer and X-ray diffraction. With the increasing of annealing temperature, the coercivity was decreased from 1.1 Oe at room temperature to 0.18 Oe at 400 °C annealing temperature, and the sensitivity of GMI effect increased from 10%/Oe to 140%/Oe. The aspect ratio of the ribbon was found to affect the excitation frequency, which leads the GMI effect to the maximum due to the shape induced demagnetization field, regardless of the annealing temperature.