Magnetic effects induced by self-ion irradiation of Fe films

Iron magnetic moment enhancement is observed following the irradiation of iron films with 490 keV $\mathrm{F}{\mathrm{e}}^{+}$ at room temperature. The iron magnetic moment enhancement increases to saturation with irradiation dose. The enhanced magnetic moment decays exponentially to its value before the irradiation with a time constant of 5.2 months. The iron magnetic moment enhancement is attributed to the creation of vacancy clusters having a concentration of about 20%, whereas the relaxation effects is attributed to the dissociation of these clusters.

Figure 1

Normalized lattice constant and grain size as a function of dose. The solid line is a least squares fit of Eq. (1) to the data (see text for details).

Figure 2

Magnetization hysteresis curves: (a) open circles before irradiation and (b) solid circles after 72 dpa irradiation with 490 keV $\mathrm{F}{\mathrm{e}}^{+}$. The inset is a zoom in of the hysteresis loop around zero field.

Figure 3

(a) $R^{+}{Q}^4$ and (b) $R^{-}{Q}^4$ data versus the scattering vector. The solid line is a least squares fit to the data corresponding to a magnetic moment for Fe of $2.5{\mu }_B/\mathrm{atom}$. The dotted, dashed, and dashed-dotted lines correspond to models with Fe magnetic moments of $2.1{\mu }_B/\mathrm{atom}, 2.4{\mu }_B/\mathrm{atom}$, and $2.6{\mu }_B/\mathrm{atom}$, respectively.

Figure 4

Atomic magnetic moment as a function of dpa. The solid line is a least squares fit of Eq. (1) (see text for details).

Figure 5

Atomic magnetic moment of the Fe film irradiated at 72 dpa as a function of the time elapsed from the $\mathrm{F}{\mathrm{e}}^{+}$ irradiation. The solid line is a least squares fit to the data of Eq. (2).