Effect of ion beam irradiation on magnetism of Fe(100) outermost surfaces studied by spin-polarized ion scattering spectroscopy

We study the effect of 2 keV Ar⁺ ion beam irradiation (IBI) on the outermost surface magnetism of an Fe(100) film by spin-polarized ion scattering spectroscopy (SP-ISS). We found that the coercivity of the outermost surface is enhanced with IBI. On the other hand, spin polarization is independent of IBI. These effects of IBI on surface magnetism are discussed in terms of morphology and atomic arrangement of the surface analyzed by ISS and reflection high-energy electron diffraction. The variation of coercivity with respect to the average iron film thickness d followed a power law d^? n with the assumption that d is linearly dependent on the IBI time.