Kim M, Xu S G, Berdyugin A I, Principi A, Slizovskiy S, Xin N, Kumaravadivel P, Kuang W, Hamer M, Krishna Kumar R, Gorbachev R V, Watanabe K, Taniguchi T, Grigorieva I V, Fal'ko V I, Polini M, Geim A K
School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK.
National Graphene Institute, University of Manchester, Manchester, M13 9PL, UK.
Nat Commun. 2020 May 11;11(1):2339. doi: 10.1038/s41467-020-15829-1.
Electron-electron interactions play a critical role in many condensed matter phenomena, and it is tempting to find a way to control them by changing the interactions' strength. One possible approach is to place a studied system in proximity of a metal, which induces additional screening and hence suppresses electron interactions. Here, using devices with atomically-thin gate dielectrics and atomically-flat metallic gates, we measure the electron-electron scattering length in graphene and report qualitative deviations from the standard behavior. The changes induced by screening become important only at gate dielectric thicknesses of a few nm, much smaller than a typical separation between electrons. Our theoretical analysis agrees well with the scattering rates extracted from measurements of electron viscosity in monolayer graphene and of umklapp electron-electron scattering in graphene superlattices. The results provide a guidance for future attempts to achieve proximity screening of many-body phenomena in two-dimensional systems.
电子-电子相互作用在许多凝聚态物质现象中起着关键作用，因此人们很想找到一种通过改变相互作用强度来控制它们的方法。一种可能的方法是将研究的系统置于金属附近，这会引发额外的屏蔽，从而抑制电子相互作用。在此，我们使用具有原子级薄栅极电介质和原子级平整金属栅极的器件，测量了石墨烯中的电子-电子散射长度，并报告了与标准行为的定性偏差。由屏蔽引起的变化仅在几纳米的栅极电介质厚度时才变得重要，这比电子之间的典型间距小得多。我们的理论分析与从单层石墨烯中电子黏度测量以及石墨烯超晶格中倒逆电子-电子散射测量所提取的散射率非常吻合。这些结果为未来在二维系统中实现多体现象的近邻屏蔽尝试提供了指导。
