Tuning electron correlation in magic-angle twisted bilayer graphene using Coulomb screening
ORAL
Abstract
In this talk, we report a novel device geometry, where the magic-angle twisted bilayer graphene (tBLG) [1-2] and a Bernal bilayer graphene (BLG) are separated by an insulating barrier with thickness of 3nm. The close proximity allows charge carriers from BLG to screen Coulomb interaction in the tBLG. Activation energy gap measurement shows that the correlated insulating states become less robust as Coulomb interaction is weakened by screening, demonstrating our ability to directly control the strength of electron correlation in the moire flatband. Most remarkably, transport measurements also demonstrate the significant influence Coulomb screening has on the robustness of the superconducting phase: at optimal doping, the stability of superconductivity is enhanced by the introduction of Coulomb screening [3]. Our results provide new insights into the nature of the superconducting phase in tBLG.
References:
[1] Yuan Cao, Valla Fatemi, et al., Nature 556, 43-50 (2018).
[2] Yuan Cao, Valla Fatemi, et al., Nature 556, 80-84 (2018).
[3] Xiaoxue Liu, Zhiwang, et al., arXiv:2003.11072 (2020).
References:
[1] Yuan Cao, Valla Fatemi, et al., Nature 556, 43-50 (2018).
[2] Yuan Cao, Valla Fatemi, et al., Nature 556, 80-84 (2018).
[3] Xiaoxue Liu, Zhiwang, et al., arXiv:2003.11072 (2020).
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Presenters
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Xiaoxue Liu
- Brown University
- Department of Physics, Brown University