Slow and highly confined plasmons observed in atomically thin TaS2

作者：Hue T. B. Do, Meng Zhao, Pengfei Li, Yuki Soh, Jagadesh Rangaraj, Bingyan Liu, Tianyu Jiang, Xinyue Zhang, Jiong Lu, Peng Song, Jinghua Teng, Michel Bosman · 发表于：Nature Communications · 年份：2025 · DOI：10.1038/s41467-025-60814-1 · 被引用次数：5 · 研究领域：Plasmonic and Surface Plasmon Research、Gold and Silver Nanoparticles Synthesis and Applications、Surface and Thin Film Phenomena

Extreme light confinement down to the atomic scale has been theoretically predicted for ultrathin, Ta-based transition metal dichalcogenides (TMDs). In this work, we report the observation of highly confined plasmons in 2H-TaS2 monolayers and bilayers via momentum-resolved electron energy loss spectroscopy (q-EELS), with a resolution of 0.0056 Å−1. Momentum-dispersed two-dimensional (2D) plasmon resonances were found to exhibit a lateral confinement ratio up to 300 at large wave vectors of q = 0.15 Å−1 and slow light behaviour with a group velocity ~10-4c. Moreover, we observed a transition from 2D to 3D Coulomb interaction in the high-momentum regime, equivalent to light confinement volumes of 1-2 nm3. Remarkably, the resonant modes do not enter the electron-hole continuum, potentially enabling even further enhanced optical field confinements for this material at cryogenic temperatures. 2D Ta-based transition metal dichalcogenides have been predicted to host highly confined plasmons, but their observation has been lacking. Here, the authors report momentum-resolved electron energy loss spectroscopy measurements of 2H-TaS2 monolayers and bilayers, showing plasmon resonances with lateral confinement up to 300 and group velocity down to ~10−4c at large wave vectors.