期刊
SCIENCE
卷 371, 期 6535, 页码 1261-+出版社
AMER ASSOC ADVANCEMENT SCIENCE
DOI: 10.1126/science.abb8754
关键词
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资金
- Brown University
- MRI award [DMR-1827453]
- NSF [DMR-1916958]
- National High Magnetic Field Laboratory through NSF [DMR-1157490]
- State of Florida
- EMEXT Element Strategy Initiative to Form Core Research Center [JPMXP0112101001]
- CREST, JST [JPMJCR15F3]
This study introduces a new device geometry to continuously tune the strength of electron-electron Coulomb interaction within twisted bilayer graphene, revealing opposite effects of charge screening on insulating and superconducting states.
Controlling the strength of interactions is essential for studying quantum phenomena emerging in systems of correlated fermions. We introduce a device geometry whereby magic-angle twisted bilayer graphene is placed in close proximity to a Bernal bilayer graphene, separated by a 3-nanometer-thick barrier. By using charge screening from the Bernal bilayer, the strength of electron-electron Coulomb interaction within the twisted bilayer can be continuously tuned. Transport measurements show that tuning Coulomb screening has opposite effects on the insulating and superconducting states: As Coulomb interaction is weakened by screening, the insulating states become less robust, whereas the stability of superconductivity at the optimal doping is enhanced. The results provide important constraints on theoretical models for understanding the mechanism of superconductivity in magic-angle twisted bilayer graphene.
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