Engineering of magnetic properties and magnetoimpedance effect in Fe-rich microwires by reversible and irreversible stress-annealing anisotropy

Abstract

Herein, by using both hysteresis loops and the Giant magnetoimpedance, GMI, measurements, the magnetic properties of amorphous FeSiBC microwires have been thoroughly analyzed paying attention on the influence of annealing (under stress or without stress) on the GMI effect and magnetic properties of Fe–Si–B–C microwires. We observed that stress annealing allows the induction of transverse magnetic anisotropy and the GMI effect improvement. This stress-annealing induced anisotropy depends on the stress-annealing conditions: annealing time and stress applied during the annealing and can be partially annealed out by subsequent furnace annealing. However, the reversibility of the stress-annealing induced anisotropy depends on the stress-annealing conditions. Particularly, most of the transverse induced magnetic anisotropy obtained by stress-annealing at high stresses values is irreversible. Stress-annealing followed by annealing without stress allows further improvement of the GMI effect in Fe–Si–B–C microwires in a wide frequency range.Coercivity, remanent magnetization, and magnetoimpedance ratio of FeSiBC microwires can be tuned by annealing conditions: annealing time and stress.All studied microwires present GMI hysteresis. The sample with the highest GMI ratio presents the lowest GMI hysteresis.Observed experimental results are discussed considering relaxation of internal stresses, compressive “back-stresses” arising after stress annealing and topological short range ordering.