Giant magnetoimpedance effects in the soft ferromagnet ${\mathrm{Fe}}_{73.5}$Cu${\mathrm{Nb}}_3$${\mathrm{Si}}_{13.5}$${\mathrm{B}}_9$

The components of the resistance $R$ and the reactance $X$ of the complex impedance $Z=R+iX$, as well as the relative effective permeability ${\mu }^{\prime }$, for as-quenched and nanocrystalline ${\mathrm{Fe}}_{73.5}$Cu${\mathrm{Nb}}_3$ ${\mathrm{Si}}_{3.5}$ ${\mathrm{B}}_9$ ribbons have been studied as functions of drive current frequency (1 kHz to 13 MHz) and longitudinal magnetic field (-75 to 75 Oe). For as-quenched samples, a mostly resistive feature was found over the whole frequency range. The magnetoimpedance effect was more sensitive for nanocrystalline samples: at 3 MHz, $R$ and $X$, respectively, increased 10% and 16% at a longitudinal field of 4 Oe, or decreased 47% and 33% at a 75 Oe field. The magnetic responses of both $R$ and $X$ for nanocrystalline samples showed a maximum at about 4 Oe, whereas there was no maximum for as-quenched samples. The field dependence of effective permeability for nanocrystalline samples showed a sharp reduction at about 4 Oe; which is believed to be the anisotropy field.