The relaxation of hollow atoms produced by slow multiply charged ions impinging on surfaces produces characteristic Auger electron spectra. These spectra, which serve as fingerprints of the interaction, can be used to probe local spin ordering at surfaces by relating changes in the intensities of different spin states to local spin polarization at the surface. The area from which the electrons are captured is of the order of a few ${\AA }^2$, only. The potential of the method is illustrated by ${\mathrm{He}}^{2+}$ and ${\mathrm{N}}^{6+}$ ions interacting with a ferromagnetic Ni(110) crystal. From the Auger spectra we determine a spin polarization of $\approx -90\%$ at room temperature.

• Received 20 October 2005

DOI:https://doi.org/10.1103/PhysRevLett.96.177601