2025/02/13(Thu) 10:30 -12:00 五樓第一會議室 5F, 1st Meeting Room
Title
Moiré Engineering for Tunable Numbers of Flat Bands and Its Quantum Geometry
Speaker
洪逸群先生 (Northeastern University, US) Mr. Yi-Chun Hung (Northeastern University, US)Abstract
Moiré engineering, especially using twisted bilayers, has provided novel control on the creation of flat bands that are isolated from other high-energy bands through the emerging moiré potential. This advances studies like the quantum geometric effects of physical observables and novel interacting phases. On the other hand, flat bands can also be generated from the geometric structures of an untwisted lattice, such as the kagome lattice. Such a lattice-geometry-induced flat band lies robustly at zero energy with exactly flat dispersion in certain lattices, such as Lieb and dice lattices. Yet, combining these flat band-generating mechanisms remains unexplored. In this talk, I will briefly introduce moiré and flat band physics and present our recent findings on twisted bilayer dice and Lieb lattices [1]. We demonstrate that the number of flat bands within can be tuned by the twist angle, generating thousands of flat bands near the Fermi level at small twist angles. The interlayer tunneling further isolates those flat bands from other high-energy bands. We further proposed possible material realizations of our model. These discoveries offer new insights into flat band physics through moiré engineering.
Reference:
[1] Xiaoting Zhou*, Yi-Chun Hung*, Baokai Wang*, and Arun Bansil, Generation of Isolated Flat Bands with Tunable Numbers through Moiré Engineering, Physical Review Letters 133, 236401 (2024) Editors’ Suggestion
Language
演講語言 (Language): in English