Remote epitaxial frustration

Remote epitaxy promises to relax the lattice and chemical mismatch challenges of conventional epitaxy, to enable low defect density and chemically abrupt heterostructures and etch-free synthesis of single crystalline membranes. However, smoking gun experimental evidence for a true remote mechanisms remains elusive because most observations can be explained by alternative mechanisms which are often macroscopically indistinguishable from remote epitaxy [1]. Here, using GdAuGe films grown on graphene/SiC (0001), we present two long-range signatures of a remote mechanism that cannot be explained by the leading alternatives: (1) a two atomic layer thick frustrated interlayer at the GdAuGe/graphene interface and (2) a 30 degree rotated epitaxial relationship between GdAuGe film and SiC substrate. First principles and analytical theory [2] suggest these signatures arise from remote epitaxial frustration, i.e. a competition among epitaxy of GdAuGe to the remotely screened substrate, to graphene, and to the graphene/SiC interface reconstruction. Our results highlight the importance of considering the multiple contributions to the total lattice potential above graphene-covered surfaces [3]. Moreover, our work demonstrates that tuning the relative amplitudes and frequencies of these potentials provides opportunities to push beyond the current epitaxial paradigm, in which the film mimics the structure of the substrate. Rather, remote frustration enables the intentional disruption of long-range translational order, towards stabilizing new interfacial glasses and quasicrystals, and the direct synthesis of twisted Moire superstructures.