报告题目：Emerging Ground and Excited State Interlayer Exciton Dipoles in Multilayer 2H-MoSe2
报 告 人：封顺（洛桑联邦理工学院）
报告时间：2023年6月19日（周一）上午10:00
报告地点：beat365体育官方网站新楼多功能厅（D-505）
报告摘要：
The fundamental properties of an exciton are determined by the spin, valley, energy, and spatial wavefunctions of the Coulomb bound electron and hole. In van der Waals materials, these attributes can be widely engineered through layer stacking configuration to create highly tunable interlayer excitons with static out-of-plane electric dipoles, at the expense of the strength of the oscillating in-plane dipole responsible for light-matter coupling. Here we show that interlayer excitons in bi- and tri-layer 2H-MoSe2 crystals exhibit electric-field-driven coupling with the ground (1s) and excited states (2s) of the intralayer A excitons. We demonstrate that the hybrid states of these distinct exciton species provide strong oscillator strength, large permanent dipoles (up to 0.73 ± 0.01 enm), high energy tunability (up to ~ 200 meV), and full control of the spin and valley characteristics such that the exciton g-factor can be manipulated over a large range (from -4 to +14). Further, we observe the bi- and tri-layer excited state (2s) interlayer excitons and their coupling with the intralayer excitons states (1s and 2s). Our results, in good agreement with a coupled oscillator model with spin (layer)-selectivity and beyond standard density functional theory calculations, promote multilayer 2H-MoSe2 as a highly tunable platform to explore dipolar physics with strong light-matter interactions, towards collective phenomenon like both Bose Hubbard physics and Bose Einstein condensation in a solid-state platform.
References: https://arxiv.org/abs/2212.14338, paralleled WSe2 work in Nat. Nanotechnol. (2023) https://doi.org/10.1038/s41565-023-01350-1
报告人简介：
Dr. Shun FENG obtained his Bachelor degree in physics in Wuhan University in 2014 and his PhD degree in physics in August 2019 in Nanyang Technological University, Singapore, supervised by Prof. Ting YU. His PhD study was focused on spectroscopic investigation of tunable light emission of intralayer excitons in monolayer TMDs, covering topics of optical bio-sensing, charge tunable spin-valley properties and tailored quantum emission. After graduation he started the postdoctoral study in Heriot-Watt University, Edinburgh, UK in November 2019, supervised by Prof. Brian Gerardot. As a postdoc he extended his interest to intra-/interlayer excitons in multilayer TMD semiconductor homo- and heterostructure, including charge and electric field tunable intra/interlayer exciton absorption and moiré-trapped interlayer exciton dynamics. In 2023 he is moving to EPFL Switzerland as an incoming postdoc in Prof. Andras Kis group. He has won several conference awards in national conferences and received the prestigious Marie Curie Fellowship in 2021.
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