An asymmetric aluminum active quantum plasmonic device

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Plasmonic nanostructures exhibit intense electromagnetic hotspots.
• Electrical manipulation offers reversible control of plasmon resonances via bias voltage.
• Asymmetric nanoparticle dimers model nanoparticle-on-film plasmonic antennas.

Purpose of the Study:

• Investigate quantum effects on an asymmetric aluminum nanoparticle dimer using TDDFT.
• Model nanoparticle-on-film coupling for plasmonic antenna applications.
• Examine electrical tunability of plasmon resonances in nanoscale junctions.

Main Methods:

• Time-dependent density functional theory (TDDFT) simulations.
• Analysis of an asymmetric aluminum nanoparticle dimer (nanoparticle on a cuboid).
• Investigation of plasmon resonance shifts and appearance of charge transfer plasmons with decreasing gap distance.

Main Results:

• Redshift of dipolar gap plasmon (DGP) and emergence of charge transfer plasmon (CTP) as distance decreases.
• Observation of a smooth transition from capacitive to conductive coupling in aluminum.
• Identification of a DGP-CTP crossover distance (∼6 Å) with distinct CTP and anti-bonding gap plasmon modes.
• Demonstration of reversible tuning of plasmon modes via electrical bias by modifying tunneling barrier conductance.

Conclusions:

• Asymmetry is crucial for active plasmonic devices utilizing electrical bias.
• Electrical bias enables reversible tuning of plasmon modes over a wider wavelength range.
• Quantum effects significantly influence plasmon behavior in nanoscale junctions.