Off-diagonal magnetoimpedance in field-annealed Co-based amorphous ribbons

Abstract

The off-diagonal magnetoimpedance in field-annealed CoFeSiB amorphous ribbons was measured in the low-frequency range using a pickup coil wound around the sample. The asymmetric two-peak behavior of the field dependence of the off-diagonal impedance was observed. The asymmetry is attributed to the formation of a hard magnetic crystalline phase at the ribbon surface. The experimental results are interpreted in terms of the surface impedance tensor. It is assumed that the ribbon consists of an inner amorphous region and surface crystalline layers. The coupling between the crystalline and amorphous phases is described through an effective bias field. A qualitative agreement between the calculated dependences and experimental data is demonstrated. The results obtained may be useful for development of weak magnetic-field sensors.

The effect of surface crystalline layers on asymmetric off-diagonal magnetoimpedance in field-annealed CoFeSiB amorphous ribbons

“…Recently, the off-diagonal magnetoimpedance in fieldannealed Co-based amorphous ribbons has been reported [4]. The asymmetric two-peak behavior of the field dependence of the off-diagonal impedance has been observed.…”

“…The coupling between the amorphous bulk and the crystalline layers results in the asymmetry in the GMI response. To explain the experimental data [4], it has been suggested that the surface layers have different thickness. In this work, we present the study of the influence of the crystalline layers on the off-diagonal magnetoimpedance in Co-based amorphous ribbons.…”

“…It is assumed that the field-annealed ribbon consists of the amorphous bulk and two surface crystalline layers [4,8]. Due to the presence of the annealing field, an effective unidirectional anisotropy is induced in the surface layers.…”

“…The calculations are based on a solution of Maxwell equations together with the Landau-Lifshitz equation [4]. The transverse magnetic field induced by the AC current has the anti-symmetrical distribution over the ribbon thickness.…”

Off-Diagonal Magnetoimpedance Dependence of Magnetostriction and Anisotropy in Co-Based and Fe-Based Amorphous Ribbons

“…This effect is referred to as off-diagonal MI. Off--diagonal MI has been measured before in amorphous magnetic ribbons and wires [7,8]. * corresponding author; e-mail: grande@uniovi.es…”