Giant Magnetoimpedance Effect in a Sandwiched Structure of as-Quenched FeNiCrSiB Ribbons

The giant magnetoimpedance (GMI) effect and effective permeability ratio in a QFR/Cu/QFR sandwiched structure are studied, where QFR stands for the as-quenched FeNiCrSiB amorphous ribbon. Remarkable GMI effects are obtained in the QFR/Cu/QFR sandwiched structure without annealing. The maximum values of the longitudinal and transverse GMI ratios at 0.5 MHz are 282% and 408%, respectively. Correspondingly, the maximum effective permeability ratios at 0.5 MHz are 326% and 1013% in longitudinal and transverse field, respectively. These large GMI values are attributed to the high effective permeability of the sample due to the closed alternating current (ac) magnetic flux path in the sandwiched structure, and large permeability variation induced by the magnetic field.