Magnetic properties and giant magnetoimpedance of nanocrystalline Fe92−xZr7BxCu1 ribbons

Abstract

The influence of substitution of B for Fe on the microstructure, magnetic properties, and giant magnetoimpedance (GMI) effect has been studied for the nanocrystalline soft magnetic ribbons Fe92−2Zr7BxCu1 (x=2,4,6,8,10) annealed at 873 K for 20 min. The experimental results show that the thermal stability of the amorphous precursor is enhanced and the body-centered-cubic phase grains become smaller with increasing B content. The coercive force Hc exhibits a minimum of 2.51 A/m for the ribbon with x=8, where the effective permeability reaches the maximum. The frequency and field dependence of GMI effect is very sensitive to B content. For the ribbon with x=8, The maximal GMI ratio (ΔZ/Z)ΔZ/Z=[Z(H)−Z(Hmax)]/Z(Hmax) is about 260% at f=6.5 MHz, and the maximal sensitivity reaches value up to about 0.88% (A/m)−1 (66.6% Oe−1) at f=10.5 MHz. The correlation between the magnetic properties and the GMI effect shows that the excellent soft magnetic properties and proper transverse anisotropy play a decisive role in the occurrence of the GMI effect.

Annealing temperature dependance of magnetic properties and magneto-impedance effect in CoZrB alloys

“…Many previous research results have confirmed that maximum MI ratio increases with increasing driving frequency, and then decreases when frequency excesses some a critical value [29,30]. The decrease of MI effect at high frequencies is due to the strong suppression of the domain wall movement by eddy current effect, which causes an extreme decrease of permeability [29,[31][32][33]. As the highest frequency can only reach 1110 kHz under our experimental conditions, we are unable to give full Z/Z(%) max -frequency curves for Co 72 Zr 8 B 20 in the as-quenched state and annealed at 495 • C. In many cases, with increasing frequency the MI effect increases due to involvement of the rotational processes.…”

“…5 that no MI response is obtained in the sample annealed at 630 • C at any of the measuring frequencies. Many previous research results have confirmed that maximum MI ratio increases with increasing driving frequency, and then decreases when frequency excesses some a critical value [29,30]. The decrease of MI effect at high frequencies is due to the strong suppression of the domain wall movement by eddy current effect, which causes an extreme decrease of permeability [29,[31][32][33].…”

Effect of quenching wheel speed on the structure, magnetic properties and magnetoimpedance effect in Co64Fe4Ni2B19−xSi8Cr3Alx (x=0, 1 and 2) melt-spun ribbons

“…The initial increase in the MI values is assigned to decrease the skin effect, which causes the transverse permeability to increase resulting in a net increase in magnetoimpedance. The decrease in MI values at higher frequencies than 5 MHz is caused by the damping wall motion as an outcome of eddy currents around domain walls [14]. MIR curves measured at 5 MHz as a function of the applied field for the samples with composition Co 64 Fe 4 Ni 2 B 18 Si 8 Cr 3 Al 1 at different quenching rates is reported in Fig.…”

Influence of quenching rate on the structural, soft magnetic and magnetoimpedance properties of melt-spun Co69Fe7Si14B10 alloy

“…The initial increase in the MI values is attributed to decrease in skin effect which causes the transverse permeability to increase resulting in a net increase in magnetoimpedance. The decrease in MI values at higher frequencies is due to the damping of domain wall motion as a result of eddy currents around domain walls [20]. Fig.…”