腾讯会议：468-247-276

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报告摘要：
Interfaces between two-dimensional (2D) materials offer a fertile ground for emergent structures and functionalities, most notably, moiré superlattices formed in twisted bilayers that can host correlated and superconducting states. Recent studies in graphene systems have demonstrated that even richer superlattice structures and electronic behaviors can emerge in beyond-bilayer heterostructures. However, achieving such exquisite structural and interactional control in semiconducting 2D materials has remained elusive. In this talk, I will discuss two of our recent efforts to address this challenge. First, I will introduce a new excitonic material platform based on a tetralayer 2D semiconductor heterostructure that hosts a highly polarizable interlayer exciton species. In this system, the exciton dipole length, in-plane radius, and binding energy can be continuously tuned in situ over a broad range, allowing direct control over exciton–exciton interactions and the nature of excitonic many-body phase transitions. These results establish exciton geometry as a new, continuously tunable materials parameter and open pathways toward exciton-based quantum phase-transition simulators. Second, I will present our design of emergent supermoiré lattices in a hetero-tetralayer system, where two distinct yet highly interfering bilayer moiré superlattices coexist. By tuning the relative stacking order (R- vs. H-type) and twist angle between the parental bilayers, we achieve new classes of long-range supermoiré patterns that are fundamentally inaccessible in conventional bilayer systems. Together, these studies demonstrate how crafting complex 2D heterostructures enables nontrivial control over both electronic interactions and structural landscapes, offering new opportunities in quantum materials design and discovery.

报告人简介：
Yusong Bai is an Assistant Professor in the Department of Chemistry at Brown University. He received his bachelor’s degree from Beihang University in 2011, and subsequently earned his Ph.D. in Physical Chemistry from Duke University in 2017 under the supervision of Prof. Michael Therien. During his doctoral work, Yusong pioneered studies on the dynamics and spectroscopic fingerprints of trions in carbon nanotubes. Following his Ph.D., he conducted postdoctoral research at Columbia University with Prof. Xiaoyang Zhu, focusing on the spectroscopy of two-dimensional semiconductors. Yusong joined Brown University and began his independent research career in August 2022.
Yusong Bai is the recipient of multiple honors and awards, including the Petroleum Research Fund (PRF) award from the American Chemical Society, the Spectroscopy Society of Pittsburgh Award, the DARPA Advanced Research Concept Award, and the NSF Research Infrastructure Improvement Program Fellowship.

邀 请 人：汪非凡 副研究员

联 系 人：王慧颖 why@iphy.ac.cn