Scattering of light by plasmonic nanoparticles is classically described using bulk material properties with infinitesimally thin boundaries. However, because of the quantum nature of electrons, real interfaces have finite thickness, leading to nonclassical surface effects that influence light scattering in small particles. Electrical gating offers a promising route to control and study these effects, as static screening charges reside at the boundary. We investigate the modulation of the surface response upon direct electrical charging of single plasmonic nanoresonators. By analyzing measured changes in light scattering within the framework of surface response functions, we find the resonance shift well accounted for by modulation of the classical in-plane surface current. Unexpectedly, we also observed a change in the resonance width, indicating reduced losses for negatively charged resonators. This effect is attributed to a nonclassical out-of-plane surface response, extending beyond pure spill-out effects. Our experiments pave the way for electrically driven plasmonic modulators and metasurfaces, leveraging control over nonclassical surface effects.

中文翻译：

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单个等离子体纳米谐振器中的表面响应调制


等离子体纳米粒子的光散射通常使用具有无限小薄边界的块状材料特性来描述。然而，由于电子的量子性质，实界面的厚度有限，导致影响小粒子中光散射的非经典表面效应。电门控为控制和研究这些效应提供了一种很有前途的途径，因为静电屏蔽电荷驻留在边界处。我们研究了单个等离子体纳米谐振器直接充电后表面响应的调制。通过分析表面响应函数框架内测得的光散射变化，我们发现谐振偏移可以通过调制经典的面内表面电流来很好地解释。出乎意料的是，我们还观察到谐振宽度的变化，表明带负电的谐振器的损耗减少了。这种效应归因于非经典的平面外表面响应，超出了纯粹的溢出效应。我们的实验为电驱动等离子体调制器和超表面铺平了道路，利用对非经典表面效应的控制。