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 Angstrom(2), only. The potential of the method is illustrated by He(2+) and N(6+) ions interacting with a ferromagnetic Ni(110) crystal. From the Auger spectra we determine a spin polarization of approximately 90% at room temperature.

Slow, multiply charged ions interacting with surfaces provide a tool for accessing surface properties on a very short length scale. Using characteristic KLL Auger electron emission from He ** atoms formed in front of a ferromagnetic surface, the local spin polarization of the surface can be linked to the population probability of different spin states in doubly excited He. An atomic model is developed to describe the population of the He ** states and their decay. The influences of the surface electronic response and the projectile parameters on the shape of the Auger spectra are discussed. Subsequently, the model is applied to He 2+ on Ni͑110͒ to extract the surface spin polarization dependence on the crystal temperature from the changes in the relative intensities of Auger peaks corresponding to different spin states. By choosing different scattering conditions, magnetic information on nanometer scale can be obtained.

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