The giant magneto-impedance effect (GMI) has been measured in commercial Hy
Mu80(R) permalloy wires, submitted to different treatments (annealing and c
old-drawing). Although hysteresis measurements show quasibistable magnetic
behavior, GMI variations as high as 160% can be found in the frequency rang
e 1-10 MHz. The frequency dependence of the GMI is also analyzed in terms o
f a nonhomogeneous anisotropy distribution. (C) 1998 American Institute of
Physics.