  The resistive and reactive components of magneto-impedance was studied for
the as-quenched and microwave annealed amorphous Fe73.5Nb3Cu1Si13.5B9 ribbon as
a function of biasing d.c magnetic fields (-60 to +60 Oe) and excitation
frequencies (0.1, 1, 10 and 20MHz). The magneto-impedance (both components)
response was much reduced for the microwave annealed ribbon and the changes
were more discernable at higher excitation frequencies. The imaginary component
of magneto-impedance showed maxima at finite (non-zero) d.c magnetic fields for
both the as-quenched and microwave annealed ribbons. Magnetization measurements
performed for both the as-quenched and microwave annealed ribbons revealed the
magnetic hardness of the latter. The initial susceptibility decreases by two
orders of magnitude for the microwave-annealed ribbon. XRD measurements
indicated the transformation of the surface of the ribbon from the amorphous
state to the crystalline one.

Materials Science