Hot-electron-injection-induced symmetry breaking in bilayer MoS$_2$ probed by second-harmonic generation
Abstract
Symmetry governs the selection rules of light-matter interactions in crystalline materials, making symmetry manipulation a powerful tool for tuning their optical properties. Here, we demonstrate that the hot-electron injection from a plasmonic resonator breaks the centrosymmtry of an adjacent transition metal dichalcogenide bilayer, probed via second-harmonic generation (SHG) in a Au-nanoparticle@bilayer-MoS@Au-film hybrid system. Power-dependent SHG measurements exhibit saturation behavior, consistent with a capacitor model where interfacial charge accumulation creates a dynamic barrier limiting further electron injection. Polarization-resolved SHG measurements reveal anisotropic second-order susceptibility response under hot-electron injection, where the contrast between different susceptibility components provides a quantitative measure of symmetry-breaking anisotropy. First-principles calculations elucidate the nonlinear optical responses evolution in bilayer MoS and comfirm the anisotropic modification of susceptibility components under hot-electron injection, modeled by a perpendicular electric field. Our work establishes SHG as an effective probe of hot-electron-induced symmetry breaking in 2D materials, demonstrating a promising approach for ultrafast manipulation of material properties through controlled charge injection at the nanoscale.
Cite
@article{arxiv.2503.21238,
title = {Hot-electron-injection-induced symmetry breaking in bilayer MoS$_2$ probed by second-harmonic generation},
author = {Zhizi Guan and Zhiwei Peng and David J. Srolovitz and Jacob Khurgin and Dangyuan Lei},
journal= {arXiv preprint arXiv:2503.21238},
year = {2025}
}