Spin polarization of Auger electrons following inner-shell photoionization of highly charged boronlike ions by circularly polarized light

Spin polarization of the Auger electrons emitted from the nonradiative Auger decay $1s2{s}^{2}2{p}_{1/2}\phantom{\rule{0.16em}{0ex}}J=1\ensuremath{\rightarrow}1{s}^{2}2s\phantom{\rule{0.16em}{0ex}}{J}_{f}=1/2+{e}_{\mathrm{A}}$ following inner-shell $1s$ photoionization of boronlike ions by circularly polarized light is studied using the multiconfigurational Dirac-Hartree-Fock method and the relativistic distorted-wave theory. Special attention is paid to the effect of the Breit interaction and also to the circular polarization transfer of the ionizing light to the spin polarization. The orientation and alignment parameters of the autoionizing level $1s2{s}^{2}2{p}_{1/2}\phantom{\rule{0.16em}{0ex}}J=1$ and the intrinsic anisotropy and spin polarization parameters of the Auger decay are calculated for boronlike ${\mathrm{Mg}}^{7+}, {\mathrm{Fe}}^{21+}, {\mathrm{Mo}}^{37+}, {\mathrm{Nd}}^{55+}, {\mathrm{Au}}^{74+}$, and ${\mathrm{U}}^{87+}$ ions. The transferred spin-polarization components ${P}_{x}$ and ${P}_{z}$ and the dynamic one ${P}_{y}$ of the Auger electrons are then obtained. The dynamic polarization ${P}_{y}$ is found to be much smaller than the transferred ones due to weak alignment of the autoionizing level. It is found that the Breit interaction hardly contributes to ${P}_{x}$, whereas the situation is much different for ${P}_{z}$. For medium- and high-$Z$ ions, for example, the transferred polarization ${P}_{z}$ is significantly enhanced by the Breit interaction for the Auger electrons emitted perpendicularly to the ionizing light beam but is weakened for those along the beam. Moreover, a quite strong circular polarization transfer of the ionizing light to the Auger electrons is found, which is comparable to the polarization transfer in the linear polarization of characteristic photons [Sharma et al., Phys. Rev. A 81, 023419 (2010)] but reveals evidence of the spin polarization of Auger electrons emitted from highly charged ions. Beyond the fundamental significance, the strong circular polarization transfer to the spin polarization of the Auger electrons enables a more detailed characterization of nonmagnetic systems, magnetically ordered materials, and (anti)ferromagnets at the atomic scale.