Magnetic after-effect in amorphous Fe85 − xCrxB15 alloys

We have investigated the influence of chromium on the magnetic after-effect (MAE) of amorphous Fe85 − xCrxB15 (x = 0, 2, 3, 5 and 7) alloys. Isochronal curves were obtained for times t = 5, 10, 30, 60, 120 and 180 s in the temperature interval from 77 K up to Tc. A computer analysis was performed to evaluate the spectra of activation energies from these measurements. The spectra of activation energies have a characteristic shape with a peak at the value of 1.2–1.4 eV. The pre-exponential factors are found to lie between 4 × 10−13 and 1.1 × 10−17 s. This indicates that the MAE can be assigned to short range atomic reorientation near free volumes. It follows from the isochronal MAE measurements that the addition of Cr atoms also causes a decrease in MAE amplitude as well as a decrease in Curie temperature. The higher the Cr-contents, the lower the MAE and the preexponential factor τ0.