Extended Data Fig. 7: Reusability of a graphene-coated MAO substrate.

a, b, Microscope images of a MAO substrate after exfoliating a CFO film grown on monolayer (a) and bilayer (b) graphene, where severe damage on the surface of the MAO substrate after exfoliation of CFO grown on monolayer graphene was observed, caused by crack propagation into the substrate. No evidence of damage was observed on substrates coated with bilayer graphene because the second graphene transfer covers the macroscopic defective areas of the first graphene layer. The scale bar indicates 1 mm. c, AFM of the pristine MAO substrate surface (left) and after one cycle of CFO exfoliation (right) with a root-mean-square roughness of approximately 5.5 Å before and after exfoliation. Scale bar indicates 1 µm. d, e, Raman spectra showing the characteristic D peak, G peak and 2D peak of graphene (d) and Raman intensity mapping (e) of the 2D peak (2,685 cm⁻¹) of graphene on the MAO substrate after one cycle of CFO exfoliation, showing evidence that graphene is preserved on the MAO substrate after exfoliation, probably because the non-specific adhesion between graphene and CFO is weaker than that between graphene and MAO. Where this is not the case, we could etch off any graphene remaining on the substrate and re-deposit graphene before epitaxy. The scale bar indicates 10 µm. f, Magnetic hysteresis M of the three exfoliated CFO membranes produced on a single graphene-coated MAO substrate measured by vibrating sample magnetometry at room temperature. a.u., arbitrary units.