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QI: Fachverband Quanteninformation
QI 33: Quantum Materials and Many-Body Systems
QI 33.7: Talk
Friday, March 22, 2024, 11:15–11:30, HFT-TA 441
Visualizing the localized electrons of a kagome flat band — •Caiyun Chen1, 2, Jiangchang Zheng1, Ruopeng Yu1, Soumya Sankar1, Hoi Chun Po1, Kam Tuen Law1, and Berthold Jäck1 — 1Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China — 2Institute for Advanced Study, HKUST Jockey Club, Clear Water Bay, Kowloon, Hong Kong SAR, China
Destructive interference between electron wavefunctions on the two-dimensional kagome lattice induces an electronic flat band, which could host a variety of interesting quantum states. Key to realize these proposals is to demonstrate the real space localization of kagome flat band electrons. The extent to which the complex structure of realistic materials counteracts the localizing effect of destructive interference is hitherto unknown. We used scanning tunneling microscopy (STM) to visualize the non-trivial Wannier states of a kagome flat band at the surface of CoSn, a kagome metal. We find that the local density of states associated with the flat bands of CoSn is localized at the kagome lattice center, consistent with theoretical predictions. Our results show that these states exhibit an extremely small localization length of two to three angstroms concomitant with a strongly renormalized quasiparticle velocity, comparable to that of moire superlattices. Our findings provide fundamental insight into the electronic properties of kagome metals and present a key step for future research on emergent many-body states in these systems.
Keywords: kagome metal; flat band