Emerging flat bands in large-angle twisted bi-layer graphene under pressure

Recent experiments on magic-angle twisted bi-layer graphene have attracted intensive attention due to exotic properties such as unconventional superconductivity and correlated insulation. These phenomena were often found at a magic angle less than 1.1 degrees. However, the preparation of precisely controlled bi-layer graphene with a small magic angle is challenging. In this work, electronic properties of large-angle twisted bi-layer graphene (TBG) under pressure are investigated with density functional theory. We demonstrate that large-angle TBG can display flat bands nearby the Fermi level under pressure, which may also induce interesting properties such as superconductivity which have only been found in small-angle TBG at ambient pressure. The Fermi velocity is found to decrease monotonously with pressure for large twisted angles, e.g., 21.8 degrees. Our work indicates that applying pressure provides opportunities for flat-band engineering in larger angle TBG and supports further exploration in related investigations.

Automated summary

Recent research has shown that under pressure, large-angle twisted bi-layer graphene can exhibit flat bands near the Fermi level, potentially inducing properties such as superconductivity found in smaller-angle twisted bi-layer graphene at ambient pressure. The Fermi velocity is found to decrease monotonically with increasing pressure for large twisted angles.