Asymmetric magnetoimpedance effect and dipolar interactions of FINEMET/SiO₂/FePd composite ribbons

The dipolar interactions are investigated through the asymmetric magneto-impedance in FINEMET/SiO₂/FePd composite ribbons. The interface between the hard (FePd layer) phase and soft (FINEMET ribbon) phase is coherent by SiO₂ layer in FINEMET/SiO₂/FePd composite ribbons, which effectively induces dipolar interactions. The contribution of dipolar interaction to the bias field (H_b) by asymmetrical giant magneto-impedance and magnetic properties is analyzed. The results show that H_b response decreases with the increase of the SiO₂ layer thickness, indicating that the linear region near-zero field can be tuned by the thickness of SiO₂ layer. These results allow the GMI ratio (58%) and characteristic frequency (500 kHz) to be optimized. The transverse and longitudinal magnetic domain structures of FINEMET ribbon and FePd film are confirmed, respectively. The composite ribbons with high GMI ratio and low frequency can be applied to linear magnetic sensors.