Promotion of superconductivity in magic-angle graphene multilayers

作者：Yiran Zhang, R. Polski, C. Lewandowski, A. Thomson, Yang Peng, Youngjoon Choi, Hyunjin Kim, Kenji Watanabe, T. Taniguchi, J. Alicea, Felix von Oppen, G. Refael, S. Nadj-Perge · 发表于：Science · 年份：2022 · DOI：10.1126/science.abn8585 · 被引用次数：164 · 研究领域：Medicine

Graphene moiré superlattices show an abundance of correlated insulating, topological, and superconducting phases. Whereas the origins of strong correlations and nontrivial topology can be directly linked to flat bands, the nature of superconductivity remains enigmatic. We demonstrate that magic-angle devices made of twisted tri-, quadri-, and pentalayer graphene placed on monolayer tungsten diselenide exhibit flavor polarization and superconductivity. We also observe insulating states in the tril- and quadrilayer arising at finite electric displacement fields. As the number of layers increases, superconductivity emerges over an enhanced filling-factor range, and in the pentalayer it extends well beyond the filling of four electrons per moiré unit cell. Our results highlight the role of the interplay between flat and more dispersive bands in extending superconducting regions in graphene moiré superlattices. Description Superb graphene multilayers Graphene bilayers and trilayers consisting of monolayers twisted at just the right angle have been shown to be superconducting. To acquire a unified understanding of superconductivity in these moiré superlattices, it is desirable to increase the number of known graphene moiré superconductors. Zhang et al. fabricated samples consisting of three, four, and five graphene layers that were twisted with respect to each other in an alternating sequence. These graphene multilayers were coupled to an underlying monolayer of tungsten diselenide...