Very large magneto-impedance and its scaling behavior in amorphous Fe73.5Nb3CU1Si13.5B9 ribbon

Magneto-impedance (MI) effects have been observed for an amorphous Fe73.5Nb3CU1Si13.5B9 ribbon which has been excited by an a.c. magnetic field parallel to the length of the ribbon and by measuring the induced voltage across an external coil. Maximum relative change in MI as large as -99% was observed in the as-cast state of the ribbon at frequencies upto 1 MHz and d.c. fields H similar to 55 Oe. The relative change in MI, delta Z = [Z(H) - Z(0)]/Z(0), when plotted against scaled field H/H-1/2 was found to be nearly frequency independent; H-1/2 is the field in which delta Z reduced to half its maximum. A phenomenological formula for MI, Z (H), based on Pade approximant has been proposed to describe the scaled behavior of delta Z in a ferromagnetic material. (c) 2007 Elsevier B.V. All rights reserved.