Last year, researchers at MIT lead by Pablo Jarillo-Herrero observed superconductivity in a pair of graphene layers engineered to be slightly misaligned. Now, a team at the ICFO in Barcelona, Spain, says it has seen a host of additional correlated states in the same “magic angle” system, providing a much more detailed view of how twisted bilayer graphene behaves and opening up new ways of studying strongly-correlated physics.
According to Dmitri Efetov, the study’s lead author, magic-angle twisted bilayer graphene represents a simple system in which to investigate novel phenomena that arise due to interactions between electrons in a material. The electron density in this platform can be tuned by applying an electric field, which allows the strength of the electron-electron interactions to be varied. It also allows the material to be tuned between different phases – for example, between the superconductor and the correlated state. Being able to do this could shed light on the underlying mechanisms at play in superconductors – especially high-temperature ones based on cuprates, for which a fundamental understanding is still lacking.
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