The effect of torsion stress on the circumferential permeability of CoFeBSi amorphous wires

In this paper, a domain model and the complex inductance formalism are employed to study the effect of torsion stress on the low-frequency magnetoimpedance (MI) response of CoFeBSi amorphous wires (125 (mu)m in diameter). In particular, the torsional dependence of the calculated circumferential permeability (mu)/sub (phi)/ is found to be very sensitive to the wireʹs scalar permeability (mu)/sub dc/ which, in turn, depends inversely on the wireʹs induced anisotropy K/sub i/. Calculated (mu)/sub (phi)/ exhibited a marked increase for increased (mu)/sub dc/ and a decrease for reduced (mu)/sub dc/. Experimental spectroscopic plots of (mu)/sub (phi)/ under various torsion stresses (counter- and clockwise-oriented) which resulted in various helically induced anisotropies K/sub h/ are consistent with an enhancement/counterbalancing effect of K/sub i/ through the addition/subtraction of K/sub h/ to K/sub i/.