A closely spaced but electronically isolated electronic double-layer system is fascinating to study interlayer quasiparticle interactions and to reveal intriguing interlayer correlated states. Recent progresses in the development of graphene and other two-dimensional (2D) electronic systems have sparked renewed interest in the field of strong interlayer interactions and corresponding novel quantum phases. In particular, the highly tunable electronic properties of constituent 2D layers, together with the accessibility of ultra-small interlayer separation, enable the investigation of the drag effect in previously inaccessible strong-coupling regimes.
In this talk, I will present our recent work on the interlayer drag experiments in several graphene-based electronic double-layer systems, including: 1) Revealing a fingerprint feature of drag effect between massless and massive fermions in heterostructures consisting of monolayer graphene and bilayer graphene separated by hBN spacer. 2) 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. 3) Demonstration of a giant and highly-tunable drag effect between graphene and superconducting LaAlO3/SrTiO3 heterointerface, and a brand-new Josephson-Coulomb drag mechanism is proposed to account for such effect, rooting in the interactions between the substantially enhanced dynamical quantum fluctuations of the superconducting phases in Josephson junction arrays and the normal electrons. Our findings establish a novel platform, i.e., electronic double-layer systems, to exploit novel inter-layer quantum effects, and offer unforeseen opportunities for new-principle electronic devices.
曾长淦，中国科学技术大学教授，教育部“长江学者”特聘教授，中国科学院“百人计划”和教育部“新世纪优秀人才支持计划”入选者。主要围绕多自由度耦合的新型低维电子体系，通过多尺度实验手段，在实现高质量材料精控制备、探索特殊电子结构和拓扑量子物性关联、发展新型物性调控手段等方面开展了一系列研究工作。共发表学术论文近百篇, 包括1篇Nature，6篇Nature子刊， 14篇PRL。承担过多项国家级重要科研任务，包括中科院战略先导专项项目、国家自然科学基金委重点项目、科技部重大研究计划子课题等。