Effect of ion-implantation on magnetization processes of 3% SiFe determined by susceptibility spectrum

Rectangular 3% SiFe samples with 0° and 90° cut angles α with respect to the [0 0 1] direction were implanted by N-ion in the fluence range of n=5×10 16–5×10 18 ions/cm 2. The susceptibility spectra originating from both relaxation processes of reversible domain wall motion and magnetization rotation are separated from the complex susceptibility spectrum measured for the samples. The variation of the separated spectra with n showed that the domain wall motion is sensitively affected by the implantation while the magnetization rotation is not affected for both samples with α=0° and 90°. The static susceptibilities χ rev,dw due to reversible domain wall motion is maximum at n=5×10 17 and 5×10 16 ions/cm 2 for α=0° and α=90° samples, respectively, and significantly decreases at n=5×10 18. The relaxation frequency f rev,dw of reversible domain wall motion is nearly constant up to n=5×10 17 ions/cm 2 for both α’s, and then increases for the further increase in n. The change of χ rev,dwand f rev,dwwith n indicates that the decrease in the distance between adjacent pinning sites is the dominant effect on the magnetization by reversible domain wall motion at relatively low ion fluence, while the increase in internal stress is the significant effect at high ion fluence.