GIANT MAGNETOIMPEDANCE IN THE FERROMAGNETIC ALLOY CO75-X-FE-X-SI15B10

A room-temperature giant magnetoimpedance (GMI) effect has been observed in thin amorphous ribbons of the soft ferromagnetic alloy Co75-xFexSi15B10 at low fields, H<10 Oe. The size- and field-dependence of the effect are very sensitive to the annealing conditions and concentration x. The peak value of the magneto-impedance ratio is strongly dependent on the frequency of the measuring ac current. Values as large as 130% have been measured at 1 MHz in a sample with the zero-magnetostriction composition (x=4.6) properly annealed in a transverse field. We suggest that the frequency dependence of the GMI arises from electron scattering by ac current-induced domain-wall oscillations. © 1995 The American Physical Society.