Soft magnetic properties and giant magnetoimpedance effect in thermally annealed amorphous Co68Fe4Cr3Si15B10 alloy ribbons

Abstract

Giant magnetoimpedance (GMI) effect in amorphous soft magnetic materials has been intensively investigated owing to its promising technological applications. The GMI effect can be improved when an amorphous ferromagnetic material is subjected to proper heat treatments. In present work, in order to further improve the GMI effect in amorphous Co68Fe4Cr3Si15B10 ribbons, thermal annealing is employed to optimize the GMI effect of amorphous Co68Fe4Cr3Si15B10 ribbons. Magnetic measurements show that the soft magnetic properties of ribbons were affected significantly by thermal annealing. The saturation flux density of ribbons increases with increasing annealing temperature. Optimized annealing temperature of about 400°C gives lowest coercivity, highest permeability and electric conductivity. The frequency dependence of GMI effect in annealed Co68Fe4Cr3Si15B10 ribbons is discussed in details. The maximum GMI value of about 220% and sensitivity of about 106%/Oe were achieved at the driven frequency of 3MHz in the ribbon annealed at 400°C. It is clear that the enhanced maximum GMI ratio and sensitivity for the sample annealed is caused by its increased saturated flux density, permeability, electrical conductivity and reduced coercivity.