2025/07/08(Tue) 14:00 -15:30 一樓演講廳 1F, Auditorium
Title
Quantum Tiling of 2D Electronic Materials
Speaker
施至剛教授 (Department of Physics, The University of Texas at Austin) Prof. Chih-Kang Ken Shih (Department of Physics, The University of Texas at Austin)Abstract
Twisting two atomically thin layers of 2D electronic materials creates moiré patterns that unlock entirely new quantum phenomena—ushering in the era of quantum tiling. Much like artistic tiling fills a surface with intricate patterns, scientists can now design moiré superlattices to engineer exotic electronic states. In this talk, I will present three recent examples from our lab using twisted bilayer WSe₂ to illustrate the power of this approach.
First, at small twist angles, long-wavelength moiré superlattices form, where the presence of oppositely charged atomic layers induces swirling patterns of interlayer polarization—pseudospin skyrmions—that impart quantum geometric phases and enable topological band engineering. Scanning tunneling microscopy and spectroscopy reveal both the pseudospin textures and associated moiré band topology. [1]
Second, at a 30° twist, the moiré pattern becomes incommensurate with the atomic lattice, giving rise to a moiré quasicrystal that lacks translational symmetry but preserves long-range order through tiling rules. Despite the breakdown of Bloch’s theorem, quasi-Bragg planes emerge, leading to fractal-like mini-gaps. [2]
Third, for twist angles slightly offset from commensurate values, the system self-organizes into a periodic array of three distinct rotational domains—called a supermoiré lattice. This superstructure generates a dense set of flatbands, offering a novel platform for exploring strongly correlated moiré quantum phases. [3]
[1] Zhang, F. et al. Nat. Phys. (2025) https://doi.org/10.1038/s41567-025-02876-y
[2] Li, Y. et al. Nature 625, 494–499 (2024). https://doi.org/10.1038/s41586-023-06904-w
[3] i, Y. et al. Nat. Phys. (2025). https://doi.org/10.1038/s41567-025-02914-9
Poster
Language
演講語言 (Language): in English