Modulation of surface response in a single plasmonic nanoresonator

Area of Science:

• Condensed matter physics
• Nanophotonics
• Quantum mechanics

Background:

• Light scattering in plasmonic nanoparticles is typically modeled using bulk properties and idealized boundaries.
• Quantum effects at interfaces, due to finite electron thickness, introduce nonclassical phenomena influencing light scattering.
• Electrical gating provides a method to control and investigate these surface effects by manipulating boundary charges.

Purpose of the Study:

• To investigate the modulation of surface response in single plasmonic nanoresonators through direct electrical charging.
• To analyze the impact of electrical charging on light scattering properties and understand underlying surface effects.
• To explore the potential for electrical control over nonclassical surface phenomena in plasmonic systems.

Main Methods:

• Single plasmonic nanoresonators were subjected to direct electrical charging via gating.
• Changes in light scattering spectra were measured to probe alterations in the nanoresonator response.
• Measured scattering changes were analyzed using surface response functions to distinguish classical and nonclassical effects.

Main Results:

• Electrical charging modulated the plasmonic resonance shift, consistent with changes in the classical in-plane surface current.
• A decrease in resonance width (reduced losses) was observed for negatively charged resonators.
• This reduction in losses was attributed to a nonclassical out-of-plane surface response, beyond simple electron spill-out.

Conclusions:

• Electrical gating effectively controls plasmonic light scattering by manipulating surface currents.
• Nonclassical surface effects, particularly an out-of-plane response, significantly influence resonance width and losses.
• These findings enable the development of electrically tunable plasmonic modulators and metasurfaces.