Fe-57 transmission and conversion electron Mossbauer spectroscopy as well as XRD were
used to study the effect of swift heavy ion irradiation on stress-annealed FINEMET
samples with a composition of Fe73.5Si13.5Nb3B9Cu1. The XRD of the samples indicated
changes neither in the crystal structure nor in the texture of irradiated ribbons
as compared to those of non-irradiated ones. However, changes in the magnetic anisotropy
both in the bulk as well as at the surface of the FINEMET alloy ribbons irradiated
by 160 MeV Xe-132 ions with a fluence of 10(13) ion cm(-2) were revealed via the decrease
in relative areas of the second and fifth lines of the magnetic sextets in the corresponding
Mossbauer spectra. The irradiation-induced change in the magnetic anisotropy in the
bulk was found to be similar or somewhat higher than that at the surface. The results
are discussed in terms of the defects produced by irradiation and corresponding changes
in the orientation of spins depending on the direction of the stress generated around
these defects.
