X-ray photoelectron spectroscopic study of ordered stoichiometric FeAl fractured in situ

An ordered stoichiometric FeAl, fractured in situ in an electron spectrometer, was studied by X-ray photoelectron spectroscopy (XPS). The energy and width of the energy-loss peak in Al 2s increased from aluminum metal to FeAl. These findings indicate that the peak is a mixture of plasmon loss and interband transition. In the Fe 3p and Fe 2p spectra, no remarkable difference was observed between FeAl and elemental Fe. The peak intensity ratios of Fe 3p/Al 2p and Fe 3s were different from those calculated from Scofield's table. The observed valence band spectrum cannot be interpreted by the valence band calculation using the spin-polarized full-potential linearized augmented-plane-wave (FLAPW) method. The curve fitting of the Fe 3s spectrum gives two peaks with an intensity ratio of about 3/1. The magnetic moment of 1.7 μ_B, estimated from this ratio, is about twice that of the bulk. The features of the valence band and of the Fe 3s spectra are attributable to the magnetic ordering of the surface-slab layers.