Silver,
king among plasmonic materials, features low inelastic
absorption in the visible-infrared (vis-IR) spectral region compared
to other metals. In contrast, copper is commonly regarded as too lossy
for actual applications. Here, we demonstrate vis-IR plasmons with
quality factors >60 in long copper nanowires (NWs), as determined
by electron energy-loss spectroscopy. We explain this result by noticing
that most of the electromagnetic energy in these plasmons lies outside
the metal, thus becoming less sensitive to inelastic absorption. Measurements
for silver and copper NWs of different diameters allow us to elucidate
the relative importance of radiative and nonradiative losses in plasmons
spanning a wide spectral range down to <20 meV. Thermal population
of such low-energy modes becomes significant and generates electron
energy gains associated with plasmon absorption, rendering an experimental
determination of the NW temperature. Copper is therefore emerging
as an attractive, cheap, abundant material platform for high-quality
plasmonics in elongated nanostructures.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.