Can Copper Nanostructures Sustain High-Quality Plasmons?

Area of Science:

• Plasmonics
• Materials Science
• Nanotechnology

Background:

• Silver is the preferred plasmonic material due to low visible-infrared (vis-IR) absorption.
• Copper is generally considered too lossy for plasmonic applications.
• High-quality plasmons are crucial for advanced optical applications.

Purpose of the Study:

• To demonstrate high-quality visible-infrared (vis-IR) plasmons in copper nanowires (NWs).
• To investigate the factors contributing to plasmon quality in elongated nanostructures.
• To explore the potential of copper as a viable plasmonic material.

Main Methods:

• Electron energy-loss spectroscopy (EELS) was used to measure plasmon quality factors.
• Comparative measurements were performed on silver and copper nanowires of varying diameters.
• Analysis focused on radiative and nonradiative loss mechanisms across a broad spectral range.

Main Results:

• Copper nanowires exhibited plasmons with quality factors exceeding 60 in the vis-IR region.
• The electromagnetic energy of these plasmons was found to reside primarily outside the copper, reducing sensitivity to losses.
• Low-energy modes (<20 meV) showed significant thermal population, enabling temperature determination.
• Relative importance of radiative and nonradiative losses was elucidated for both silver and copper.

Conclusions:

• Copper is a viable, cost-effective material for high-quality plasmonics in elongated nanostructures.
• The unique properties of copper nanowires open new avenues for plasmonic device development.
• Understanding loss mechanisms is key to optimizing plasmonic performance in different materials.