Fig. 2. Epitaxy of GdPtSb on graphene-terminated Al₂O₃ (0001).

a Schematic crystal structure of (111)-oriented cubic GdPtSb on graphene/Al₂O₃ (0001). The lattice parameter for Al₂O₃ is a = 4.785 Å and that of GdPtSb is $\frac{1}{2}{d}_{110}=4.53$ Å, corresponding to a mismatch of 2.7%. b In-plane crystal structure of GdPtSb (111). c, d Reflection high-energy electron diffraction (RHEED) patterns of graphene on Al₂O₃ after a 700 °C annealing. Black arrows mark the underlying Al₂O₃ reflections. e, f RHEED patterns for the GdPtSb film. Black arrows mark the bulk reflections. Triangles mark superstructure reflections from a 3 × surface reconstruction. Additional reflections (black asterisks) are observed that correspond to a second domain rotated by ±30°.