Auger electron diffraction study of Fe1−xNix alloys epitaxially grown on Cu(100)

Abstract We have combined Auger electron diffraction (AED), low-energy electron diffraction (LEED) and high-energy electron diffraction (RHEED) to examine the structure of Fe x Ni 1− x alloys when the Fe content approaches 65%. At this concentration, the ‘invar effect’ takes place, so the magnetization falls to zero, and the thermal expansion coefficient is very small. The Fe x Ni 1− x alloys, grown as metastable thin films by molecular-beam epitaxy on Cu(100) substrates, were studied as a function of the x stoichiometry. In contrast to the related bulk alloy compounds, we observe the collapse of the fcc-to-bcc structural transition in the Fe-rich films. Furthermore, the local atomic structure around Fe and Ni in the alloy has been simultaneously determined by the angular intensity distributions of Fe L 3 VV (703 eV) and Ni L 3 VV (848 eV) Auger electrons measured as a function of polar and azimuthal angles. For the films deposited at room temperature, we have confirmed the pseudomorphic growth morphology and the uniformity of the alloys.