Heterostrain and temperature-tuned twist between graphene/h-BN bilayers

Two-dimensional materials stacked atomically at small twist angles enable the modification of electronic states, motivating twistronics. Here, we demonstrate that heterostrain can rotate the graphene flake on monolayer h-BN within a few degrees (- 4 degrees to 4 degrees), and the twist angle stabilizes at specific values with applied constant strains, while the temperature effect is negligible in 100-900 K. The band gaps of bilayers can be modulated from similar to 0 to 37 meV at proper heterostrain and twist angles. Further analysis shows that the heterostrain modulates the interlayer energy landscape by regulating Moire pattern evolution. The energy variation is correlated with the dynamic instability of different stacking modes of bilayers, and arises from the fluctuation of interlayer repulsive interaction associated with p-orbit electrons. Our results provide a mechanical strategy to manipulate twist angles of graphene/h-BN bilayers, and may facilitate the design of rotatable electronic nanodevices.

Automated summary

The research finds that heterostrain can rotate the graphene flake within a few degrees, and the temperature effect is negligible. The band gaps of bilayers can be modulated by proper heterostrain and twist angles. Further analysis reveals that heterostrain regulates the interlayer energy landscape by controlling the evolution of Moire patterns. This result provides a mechanical strategy for manipulating the twist angles of graphene/h-BN bilayers and may facilitate the design of rotatable electronic nanodevices.