Atomic Reconstructions at Engineered van der Waals Interfaces
Date : September 17, 2025 16:00 ~
Speaker : Hyobin Yoo (Dept. of Materials Science and Engineering, SNU)
Professor : Prof. Sunghoon Jung, Prof. Joonho Jang, Prof. Yongjoo Baek
Location : 56동105호
Twisted interfaces between two-dimensional (2D) van der Waals (vdW) materials provide a unique platform for engineering symmetry, structure, and functionality at the atomic scale. By precisely controlling the stacking angle between layers, it is possible to create artificial moiré superlattices and induce lattice reconstruction at the interface. The resulting competition between interlayer commensurability and intralayer strain leads to the formation of ordered domain patterns, often accompanied by emergent electronic, optical, or ferroic properties [1].
In this talk, I will discuss how the structural characteristics of vdW interfaces, including local stacking configurations and reconstruction processes, govern the formation of domain structures and their associated functionalities. These effects are investigated through analysis of electron diffraction contrast in transmission electron microscopy (TEM) imaging. By combining TEM with modern semiconductor device fabrication techniques, we also perform operando measurements that allow direct observation of functional domain dynamics in working devices. This approach reveals the interplay between local symmetry breaking and macroscopic responses such as ferroelectric switching in twisted bilayer transition metal dichalcogenides (TMDs) [2].
Extending this framework to multilayer systems introduces additional stacking interfaces and symmetry degrees of freedom, resulting in complex domain tessellations with distinctive structural and functional characteristics [3]. These findings suggest that understanding interfacial atomic reconstruction is a key step toward interpreting and controlling emergent phenomena in twisted vdW materials.
[1] H. Yoo et al., Nat. Mater. 18, 448 (2019)
[2] K. Ko et al., Nat. Mater. 22, 992 (2023)
[3] D. Park et al., Nature 641, 896 (2025)