Ulstrup Søren, In 't Veld Yann, Miwa Jill A, Jones Alfred J H, McCreary Kathleen M, Robinson Jeremy T, Jonker Berend T, Singh Simranjeet, Koch Roland J, Rotenberg Eli, Bostwick Aaron, Jozwiak Chris, Rösner Malte, Katoch Jyoti
Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000, Aarhus C, Denmark.
Institute for Molecules and Materials, Radboud University, 6525 AJ, Nijmegen, the Netherlands.
Nat Commun. 2024 May 8;15(1):3845. doi: 10.1038/s41467-024-48186-4.
Harnessing electronic excitations involving coherent coupling to bosonic modes is essential for the design and control of emergent phenomena in quantum materials. In situations where charge carriers induce a lattice distortion due to the electron-phonon interaction, the conducting states get "dressed", which leads to the formation of polaronic quasiparticles. The exploration of polaronic effects on low-energy excitations is in its infancy in two-dimensional materials. Here, we present the discovery of an interlayer plasmon polaron in heterostructures composed of graphene on top of single-layer WS. By using micro-focused angle-resolved photoemission spectroscopy during in situ doping of the top graphene layer, we observe a strong quasiparticle peak accompanied by several carrier density-dependent shake-off replicas around the single-layer WS conduction band minimum. Our results are explained by an effective many-body model in terms of a coupling between single-layer WS conduction electrons and an interlayer plasmon mode. It is important to take into account the presence of such interlayer collective modes, as they have profound consequences for the electronic and optical properties of heterostructures that are routinely explored in many device architectures involving 2D transition metal dichalcogenides.
利用涉及与玻色子模式相干耦合的电子激发对于量子材料中涌现现象的设计和控制至关重要。在电荷载流子由于电子 - 声子相互作用而引起晶格畸变的情况下，导电态会被“修饰”，这导致极化子准粒子的形成。在二维材料中，对极化子对低能激发影响的探索尚处于起步阶段。在此，我们展示了在单层 WS 顶部的石墨烯组成的异质结构中发现层间等离子体极化子。通过在原位掺杂顶部石墨烯层期间使用微聚焦角分辨光电子能谱，我们在单层 WS 导带最小值附近观察到一个强准粒子峰以及几个与载流子密度相关的伴峰。我们的结果通过一个有效的多体模型来解释，该模型涉及单层 WS 传导电子与层间等离子体模式之间的耦合。考虑到这种层间集体模式的存在很重要，因为它们对许多涉及二维过渡金属二硫属化物的器件架构中常规探索的异质结构的电子和光学性质有深远影响。
