High frequency magneto impedance in amorphous microwires

Abstract

We report the novel results on studies of the magneto impedance (MI) effect at GHz-range in 20 μm amorphous glass-coated microwire and 40 μm melt-extracted wire with nearly-zero magnetostriction constant. Both types of wires demonstrated similar behavior although the MI effect is higher in glass-coated microwire. In high field region, when the sample is magnetically saturated, the MI dependence demonstrates typical ferromagnetic resonance behavior. In the low field region the magnetization rotation process is dominant resulting in the highest sensitivity of the impedance to magnetic field. The drawback found in the studied samples is the low field magnetic hysteresis which is undesieble for potential application. The cause of this hysteresis is found to be the helical surface anisotropy in the wires which is characterized by a nonzero angle between the anisotropy easy axis and the wire's transversal plane.