Influence of magnetic induced anisotropy on giant magnetoimpedance effects in FeCuNbSiB films

The giant magnetoimpedance (GMI) effects in radio frequency sputtered FeCuNbSiB films with a dc magnetic field applied in the process of deposition are presented, and the relation between annealing temperature and GMI ratio is investigated. The results show that 300 °C is the optimum annealing temperature, at which the GMI ratios reach the maximum values of about 38% and 27% in longitudinal and transverse dc magnetic fields, respectively, at a frequency of 13 MHz. The longitudinal magnetic responses of GMI ratios show very sharp peaks around the transverse anisotropy field, and the sensitivity can reach a value larger than 47.5%/kA/m in the field range 0.4∼6 kA/m, at 13 MHz. The frequency dependencies of the magnetoresistance and magnetoreactance indicate that at lower frequencies, the giant magnetoinductance effect is dominant, while at higher frequencies, skin effect becomes important, and the GMI effect is determined by the change of both the resistance and reactance components.