Interlayer Drag Effects in Graphene-Based Electronic Double-Layer Systems

A closely spaced but electronically isolated electronic double-layer system is a fascinating platform to study interlayer quasiparticle interactions and to reveal intriguing interlayer correlated states. Recent progress in the development of graphene and other two-dimensional (2D) electronic systems has sparked renewed interest in the study of interlayer interactions based on vertical 2D heterostructures. Especially, the highly tunable electronic properties of component layers, together with the accessibility of ultra-small interlayer separation, enable the investigation of the drag effect in previously inaccessible regimes.<br/>In this talk, I will present our recent progresses on the interlayer drag experiments in several graphene-based electronic double-layer systems, including: 1) The demonstration of signature carrier-density-dependence of drag resistance between massless and massive fermions in heterostructures consisting of monolayer graphene and bilayer graphene separated by hBN spacer [1]. 2) The discovery of a new type of quantum interference effect in inter-layer Coulomb drag, with the interference pathway comprising different carrier diffusion paths across the two constituent graphene layers [2]. 3) The discovery of a giant and highly-tunable drag effect between graphene and superconducting LaAlO₃/SrTiO₃ heterointerface, wherein a brand-new mechanism of Josephson-Coulomb drag is proposed [3]. These results have important implication for investigating interlayer-coupling-induced fascinating physics via utilizing newly-emerging 2D electronic systems.<br/><br/>References:<br/>[1] Lijun Zhu et al., Nano Lett. 20, 1396 (2020)<br/>[2] Lijun Zhu et al., Unpublished<br/>[3] Ran Tao et al., arXiv: 2003.12826v3