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High-resolution photoelectron spectroscopy with synchrotron radiation and magnetic linear dichroism in Fe 3p core-level photoemission has been used to study both the initial stages of Fe/Si(111)7×7 and Fe/Si(100)2×1 interface formation and their ferromagnetic ordering. The correlation between the phase composition, electronic structure, and magnetic behavior of the interfaces has been established. It is shown that in-plane ferromagnetic ordering of the interfaces has a threshold nature and arises after the deposition of ∼7 Å Fe in both systems. However, the remanent magnetization of Fe/Si(111) is greater than that of Fe/Si(100) due to the difference in the chemistry of the phases being formed. In the former case, it was found that at room temperature an ultrathin metastable FeSi film with the CsCl structure grows at the first stage of Fe deposition on Si. At higher Fe coverages, a Si solid solution in iron, and later an Fe film, is found to develop on FeSi. The magnetic properties of the solid solution and the Fe film of ∼15 Å thick are quite similar. At the Fe/Si(100) interface, we observe the formation of iron-rich Fe3Si, in which the average magnetic moment of Fe atoms is markedly lower than that of the Fe film. Solid-phase reactions, starting at ∼100 °C in both systems, lead to a gradual conversion of ferromagnetic phases to the nonmagnetic ε-FeSi phase, which transforms to β-FeSi2 at temperatures above 600 °C.

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