  We have investigated for the first time the combined effect of current and
stress on the GMI characteristics of vanishing-magnetostrictive Co-rich
microwires at microwave frequency. As the current-annealed wire is subject to
certain tensile stress, one can observe a drastic transformation of field
dependence of MI profiles from smooth shape of a broad peak to deformed shape
of a sharp peak with the emergence of a kink on each side. It follows that
three different regions- core, inner and outer shell -have been formed by the
combined effect of Joule annealing, current generated magnetic field and the
tensile stress. A critical field sees a drop of field sensitivity from outer to
inner shell and shifts to lower value with increasing annealing current. We
successfully adapted our core-shell model to a core-shell-shell model by
designating different anisotropy field for each region to satisfactorily
resolve the unique double-curvature shaped peaks in the field derivative MI
profiles.
