Epitaxial mosaic-like Mn5Ge3 thin films on Ge(001) substrates

Epitaxial mosaic-like Mn5Ge3 thin films were grown on Ge(001) substrates using reactive deposition epitaxy process from Mn deposition or Mn-Ge co-deposition at a substrate temperature of 250 °C using magnetron sputtering. The cross-sectional transmission electronic microscopy analyses reveal an abrupt interface at the atomic scale; two equivalent epitaxial relationships are found between the substrate and the Mn5Ge3 crystallites: Ge(001)[110] and [11¯0]∥ Mn5Ge3(11¯1)[1¯1¯0]. The chex axis of Mn5Ge3 forms an angle of 45° with the substrate plane. Rietveld analysis from a synchrotron 2-dimensional diffraction pattern revealed that remanent deformations of about 1% exist in the film. M-H measurements of 50-nm thick films elaborated by co-deposition revealed a saturation magnetization, Ms, of 636 kAm−1, whereas the films elaborated by Mn deposition saturate at different values depending on the orientation of the applied magnetic field: Ms⊥ = 545 kAm−1 and Ms∥ = 774 kAm−1. This Ms difference is attributed to shape anisotropy of crystallites and interface quality of the films.