Optical properties and plasmonic response of silver-gallium nanostructures

Silver and gallium form an alloy Ag₂Ga via a room temperature spontaneous self-assembly that exhibits remarkable mechanical and electrical properties suitable for nanoscale measurements. However, whether photon excitation of plasmons in this emerging nanomaterial is retained or not has not been established. Here, we present a thin film formation of Ag₂Ga via a spreading-reactive process of liquid Ga on an Ag film and a characterization of its dielectric function ε(E) = ε₁(E) + iε₂(E) in the photon energy range 1.42 eV ≤ E < 4.2 eV. It is observed that while the plasmon damping increases, near an energy of 2.25 eV, the real part of ε exhibits a crossing with respect to that of Ag. Furthermore, the impact of new plasmon supporting materials is discussed and in order to enable further applications in plasmonics, the possibility of photon excitation of surface plasmons in Ag₂Ga is studied.