Superconductors, orbital magnets and correlated states in magic-angle bilayer graphene

@article{Lu2019SuperconductorsOM,
  title={Superconductors, orbital magnets and correlated states in magic-angle bilayer graphene},
  author={Xiaobo Lu and Petr Stepanov and Wei Yang and Ming Xie and Mohammed Ali Aamir and Ipsita Das and C. Urgell and Kenji Watanabe and Takashi Taniguchi and Guangyu Zhang and Adrian Bachtold and Allan H. MacDonald and Dmitri K. Efetov},
  journal={Nature},
  year={2019},
  volume={574},
  pages={653-657}
}
Superconductivity can occur under conditions approaching broken-symmetry parent states1. In bilayer graphene, the twisting of one layer with respect to the other at ‘magic’ twist angles of around 1 degree leads to the emergence of ultra-flat moiré superlattice minibands. Such bands are a rich and highly tunable source of strong-correlation physics2–5, notably superconductivity, which emerges close to interaction-induced insulating states6,7. Here we report the fabrication of magic-angle twisted… 
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It is found that gaps between the flat conduction and valence bands open at neutrality over a wide range of twist angles, sometimes without breaking the system's valley projected C_{2}T symmetry.
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This study demonstrates twisted bilayer graphene to be a distinctively tunable platform for exploring correlated states by inducing superconductivity at a twist angle larger than 1.1°—in which correlated phases are otherwise absent—by varying the interlayer spacing with hydrostatic pressure.
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