Anisotropy and magnetization processes in Co-rich amorphous wires

Longitudinal magnetization curves and giant magnetoimpedance (GMI) analyses are combined to investigate the anisotropy and magnetization processes of dc-current-self-annealed ${\mathrm{Co}}_{\mathrm{68.15}}{\mathrm{Fe}}_{\mathrm{4.35}}{\mathrm{Se}}_{\mathrm{12.5}}{\mathrm{B}}_{\mathrm{15}}$ wires. The magnetization curves show an almost anhysteretic behavior with small Barkhausen jumps occurring at a critical field $H^{*}$ . This unusual shape is in very good agreement with the high resolution GMI response to the field, which reflects the circumferential bias permeability. Magnetization curves yield information on the bulk properties, while GMI allows the investigation of the surface region of the sample. The anisotropy constant is calculated using initial-magnetization curves and the resonance condition, yielding interesting conclusions concerning the inhomogeneity of the wires.