近日，美国俄亥俄州立大学Lau, Chun Ning团队研究了超导扭曲双层石墨烯中相互作用的双刃作用。2026年4月7日出版的《自然—物理学》杂志发表了这项成果。
在传统超导体中，库珀对的形成由声子介导。对于莫尔材料（如扭曲双层石墨烯）中的超导相，一个悬而未决的问题是：对的形成是由电子相互作用、声子，还是两者共同驱动的？
研究组表明，与传统超导体不同，扭曲双层石墨烯的超导性强烈依赖于介电环境。他们将扭曲双层石墨烯置于具有大且可调介电常数的块状SrTiO3基底上方短距离处。通过在魔角和大角度器件中原位提高介电常数，研究组观察到整个超导穹顶被持续抑制，并最终完全消失。
实验结果与一个理论模型定性吻合，该模型中配对机制源于由等离激元、电子-空穴对和纵向声学声子屏蔽的库仑相互作用。该研究结果凸显了该材料中超导性的非常规本质、电子相互作用及其环境在超导形成中的双刃剑角色，以及它们与关联绝缘态之间复杂的相互作用。
附：英文原文
Title: Double-edged role of interactions in superconducting twisted bilayer graphene
Author: Gao, Xueshi, Jimeno-Pozo, Alejandro, Pantaleon, Pierre A., Rajesh, Aatmaj, Codecido, Emilio, Sharifi, Daria L., Zhang, Zheneng, Liu, Youwei, Watanabe, Kenji, Taniguchi, Takashi, Bockrath, Marc W., Guinea, Francisco, Lau, Chun Ning
Issue&Volume: 2026-04-07
Abstract: In conventional superconductors, the formation of Cooper pairs is mediated by phonons. For the superconducting phases in moiré materials, such as that in twisted bilayer graphene, an unresolved question is whether pair formation is driven by electronic interactions, phonons or a combination of both. Here we show that, unlike conventional superconductors, the superconductivity in twisted bilayer graphene is strongly dependent on the dielectric environment. We place twisted bilayer graphene a short distance above a bulk SrTiO3 substrate that has a large and tunable dielectric constant. By raising the dielectric constant in situ in both magic-angle and large-angle devices, we observe steady suppression and eventually a complete extinguishing of the entire superconducting dome. The experimental results are in qualitative agreement with a theoretical model in which the pairing mechanism arises from Coulomb interactions that are screened by plasmons, electron–hole pairs and longitudinal acoustic phonons. Our results highlight the unconventional nature of the superconductivity in this material, the double-edged role played by electronic interactions and the environment in its formation, and their complex interplay with the correlated insulating states.
DOI: 10.1038/s41567-026-03243-1
Source: https://www.nature.com/articles/s41567-026-03243-1