Cross-Sectional Observations of Polymorphic FeGe Interphases

Cross-sectional microscopy is performed on FexGe1-x multilayers with steep concen- tration gradients.A profile in high angle annular dark field imaging mode demonstrates the presence of an intermetallic phase appearing brighter in Z-contrast, which is proved to be 03B1-FeGe alloy by means of associated quantitative contrast calculations.Fourier analysis of lattice fringes observed by transmission electron microscopy reveals the previously found non-magnetic interphase as ~-Fe6Ge5.These results are discussed here with reference to recent work using Mössbauer spectroscopy, kinetic ellipsometry, and Fe L-edge EELS analysis.An attempt is then made to correlate them with phase separation models involving nanometric inhomogeneities in FeGe alloys.