Atomic arrangement and spin polarization at a Ge/Fe(100) surface studied by spin-polarized ion scattering spectroscopy

Abstract

Ferromagnetic metal/semiconductor interfaces have been an important issue in spintronics research. In the present study, the very initial stage of Ge growth on an Fe(100) surface at room temperature (RT) and 633 K was investigated mainly by surface sensitive spin-polarized ion scattering spectroscopy. The incorporation of the deposited Ge into the Fe substrate occurs at 633 K while no interfacial reaction was observed at RT. The incorporation of Ge was followed by the long range super-structure formation on the surface with [1−103] and [−1−103]in matrix notation, which consists of a single Ge atomic layer. Thus, the average Ge film thickness at 633 K is always smaller than that at RT. However, the surface spin polarization of Fe decreases with the Ge deposition more rapidly at 633 K than RT. Moreover, the decay of the surface spin polarization is faster at the Fermi level compared with the total polarization. The induced spin polarization in Ge is very small and it vanishes with the super-structure formation. Those results indicate the effective spin depolarization by the Fe(100) surface with the above-mentioned Ge super-structure.