K-shell vacancies carried by swift O and Si ions inside ferromagnetic hosts.

Abstract

The single and double K-shell vacancy fractions for swift O and Si ions inside Fe and Gd foils have been measured using the probe layer technique. The measurements are carried out at velocities varying from 7.5 to 13.5${\mathit{v}}_{0}$ for Si ions and at a velocity of 7.8${\mathit{v}}_{0}$ for oxygen ions (${\mathit{v}}_{0}$=\ensuremath{\alpha}c where \ensuremath{\alpha} is the fine-structure constant and c is the speed of light). It is shown that all such available data for light ions fall on a smooth curve when plotted against the reduced velocity of the ion. These values are used along with the existing transient magnetic field data to derive the electron spin polarization acquired by the ions traveling inside ferromagnetic hosts. The degree of polarization is shown to decrease with the atomic number of the ions. This observation is, however, in disagreement with recent theoretical calculations.