Magneto-impedance effect in nanocrystalline ribbons

Abstract

Magneto-impedance effects have been studied in amorphous and nanocrystalline ribbons. Large magneto-impedance responses have been obtained in nanocrystalline samples by applying a longitudinal DC field, but not in amorphous samples. It was found that the transverse field dependences of the resistance and the reactance of nanocrystalline samples show very broad peaks at relatively high fields (above 35 Oe), while the longitudinal magnetic responses show very sharp peaks at the field of 2 - 7 Oe, sharing some common features with those reported for Co-based amorphous wire and ribbon samples, and can be understood from the same mechanism. It was also found experimentally that the properties of the longitudinal and transverse field dependences of the effective permeability of nanocrystalline samples correlates with those of the impedance, showing a sharp decrease for the longitudinal applied field and a slow decrease for the transverse applied field at a corresponding field value and, the higher the effective permeability, the larger is the magneto-impedance effect at a fixed frequency. and a sensitivity of 20% at a low field (2 Oe) are obtained in this paper.