Pseudomagnetic Fields in Graphene Strain Superlattices

Straining graphene can modify the electronic band structure and lead to the formation of giant pseudomagnetic fields. Recently it was shown that addition of superlattice periodicity to strain leads to global electronic band flattening and signatures of correlated states. Here we show an engineered approach to producing a strained graphene superlattice system. Using scanning tunnelling spectroscopy and transport measurements, together with numerical simulations, we demonstrate that a graphene monolayer placed on a SiO₂ nanosphere superlattice undergoes a band structure change with observable pseudo-Landau level formation, not only integer ones but also with fractional indices. The results are consistent with significant flattening of the electronic bands, making it ideal playground for exploring other related interaction phenomena and possibly the emergence of correlated states.<br/><br/>The authors acknowledge the support of NSF-MRSEC under award no. DMR-1720633