  Systematic measurements of stress-impedance (SI) have been carried out using
Co-rich amorphous ribbons of nominal composition Co71-xFexCr7Si8B14 (x = 0, 2)
at various excitation frequencies and bias fields and at room temperature. The
impedance, Z for both the samples was found to be very sensitive functions of
applied tensile stresses (up to 100MPa) exhibiting a maximum SI ratio as much
as 80% at low frequency ~ 0.1MHz. The nature of variation of SI changes with
the excitation frequency especially at higher frequencies in MHz region where
it exhibits a peak. Magnetization measurements were also performed to observe
the effects of applied stresses and magnetization decreased with the
application of stress confirming the negative magnetostriction co-efficient of
both the samples. Both the samples exhibited negative magneto-impedance (MI)
when the variation of Z is observed with the applied bias magnetic field, H.
The impedance as functions of applied magnetic field, Z(H), decreases with the
application of stress thus making the MI curves broader. Maximum MI ratio as
large as 99% has been observed for both the samples at low fields ~ 27Oe.
