Influence of residual stresses and their relaxation on giant magnetoimpedance of CoFeSiB metallic glasses

The magnetoimpedance effect in Co69Fe4Si15B12 melt-spun amorphous ribbons was studied in the as-quenched state and after low-temperature relaxation annealing at 473 K: The change of the impedance in the external magnetic field depends on the type of effective magnetic anisotropy and its modification by heat treatment. The maximum magnetoimpedance variation is higher in the as-quenched sample (about 420%) than in the annealed sample (about 300%). This behavior is explained to be a result of the change of the anisotropy distribution influenced by the magnetoelastic component of the effective magnetic anisotropy for the samples with well defined longitudinal anisotropy. The high magnetoimpedance effect that shows low hysteresis in the as-quenched state can be considered to be an advantage for the application of these ribbons in small field sensors.